Capabilities Archives

Surface finish is a critical aspect of many plastic parts, as it can affect the part’s performance and aesthetic appeal. To ensure that the surface finish of a plastic part meets specifications, it is important to use proper measurement techniques that are accurate and repeatable. In this post, we will discuss the use of Geometric Dimensioning and Tolerancing (GD&T) principles and profilometers for measuring surface finish on a plastic part.

What is Surface Finish?

Surface finish refers to the roughness, waviness, and lay of a surface. In other words, it is characterized by the micro-geometry of the surface, including the size, spacing, and distribution of surface features. These features can include surface roughness, such as peaks and valleys, and surface waviness, which refers to the undulations in the surface.

Why is Surface Finish Important?

Surface finish is important for a variety of reasons. For example, it can affect the performance of a part by influencing factors such as friction, wear, and corrosion resistance. Additionally, a smooth surface finish can improve the aesthetic appeal of a part and increase its marketability.

How is Surface Finish Measured?

There are several methods for measuring surface finish, including visual inspection, tactile inspection, and instrumentation-based measurements. The most commonly used instrument for measuring surface finish is a profilometer. Profilometers use a stylus to scan the surface of the part and measure the variations in surface height. Then, the data collected by the profilometer is processed to calculate the roughness parameters of the surface, including roughness average (Ra), root mean square roughness (Rq), and more.

Using GD&T Principles for Surface Finish Measurement

In order to ensure that the surface finish of a plastic part meets specifications, it is important to use a consistent and repeatable measurement method. This is where GD&T principles come into play. GD&T is a system of symbols and rules used to define the size, shape, orientation, and location of a part. With GD&T symbols and rules, designers can specify the surface finish requirements of a part, including the maximum and minimum allowable roughness parameters.

For example, the GD&T symbol for surface finish is a wavy line that is placed adjacent to a feature of size. The wavy line represents the surface roughness and the number next to it represents the maximum allowable roughness in microinches (µin). By specifying the surface finish in GD&T, designers can ensure that the part is manufactured to the correct specifications and that the surface finish is accurately measured.

Conclusion

Measuring surface finish on a plastic part is an important step in ensuring that the part meets performance and aesthetic specifications. By using GD&T principles and profilometers, designers can specify the surface finish requirements of a part and ensure that the measurement is accurate and repeatable. By using these techniques, manufacturers can produce high-quality plastic parts that meet the needs of their customers.

For more information on how we can help you achieve a desired surface finish, please reach out to our engineering department at the number on our contact page.

Most engineers approach risk management with a ho-hum attitude.

If you’re an engineer, then this probably isn’t your favorite task. For some, risk assessment is just a formality – a report passed around by different departments. So, you might take this routine easy, letting minor issues go untethered. This causes problems as those minor issues stack and becomes larger. As a result, the organization suffers a loss in both time and money.

Instead, you could avoid this with a well-executed risk assessment.

By addressing high-risk areas through a project’s lifecycle, you can save a company from disaster. This takes the hand of a seasoned engineer.

Are you about to launch a new injection molding project? Want to see how our team performs its risk assessments? Then buckle up! We’ll take you through our 9-Step Risk Assessment Process for assessing a new project request.

1: Part Design

For starters, most injection molded products follow a set of design rules. We call these Design for Manufacturing Principals or DFM. In essence, products that follow these guidelines are easy to produce and offer other molding benefits. This includes reduced scrap rate, less material use, and quicker production cycles.

The first thing we do is evaluate a drawing (or CAD) we receive for manufacturability. This process starts with looking at the product’s geometry. We do this to identify any details that are “difficult to mold”.

For example, wall thickness is one common design flaw we find in drawings. A thick wall can cause product deformation in the form of sink. And deformed products are destined to fail in the field, so we don’t want to encounter that issue!

Similarly, critical dimensions with tight tolerances are tricky. This is because of plastics’ ability to shrink. To clarify, as the product cools it shrinks based on the material’s properties. As a result, the product can shrink past the print’s callout. Of course, this is harder to avoid but doesn’t prevent us from making the product.

Instead, a subtle design change in the early stages will negate this issue before incurring avoidable costs. The result: good product with minimal engineering costs.

If you’re unsure about your part design, you can work directly with us to work out any questions you might have. Alternatively, you can look at conducting a mold flow analysis– a program that simulates how the design will fill in an injection molding environment.

2: Materials

Not everyone is an expert in material science, and you don’t need to be. But having a good understanding of the material you are working with goes a long way towards reducing your risk. You should identify whether the material you want to use is compatible with the application. Otherwise, the consequences of purchasing the “wrong material” can set your project back financially and timewise.

One of the obvious questions you should ask yourself is: “Does this material’s physical and chemical properties meet all my engineering requirements?” In other words, you’re asking yourself whether the material will work under the product’s normal operating environment. You can’t run plastic that has a low melting point in a high heat environment… It’s going to fail. But you already know that!

While that last example might be a no-brainer, some questions don’t come as easy. Here’s our top 3:

Material Availability – What does the availability of this material look like? Supply chains are as fluid (and unpredictable) as ever these days. Also, some materials require a Minimum Order Quantity (MOQ) which can impact the cost.
Process Compatibility – This comes into play with secondary processes such as over-molding or ultrasonic welding. Does the material you selected play well with others?
Dimensional Stability – Does your product require tight tolerances? Well, a well-known quality of plastic is that it shrinks! The amount that plastics shrink varies between each material and each formulation. Just something to keep an eye on!

Ultimately, your best resource for plastic is a materials supplier. Our network of materials suppliers can offer design guides, datasheets, spec sheets, and more. We often involve these suppliers early in the process just so we have all the necessary information in hand and can eliminate potential risks.

3: Tooling

When looking at risk assessment for a new mold build, we exercise a lot of information from other areas that were covered in the previous sections. This includes part geometries, material selection, and labor usage (see automatic molds vs operator-required molds). The goal at this stage is to confirm that the mold’s capability matches the project’s requirements in terms of value, volume, and efficiency.

For instance, one way we facilitate harmony between reality and expectations is through production volume. If your annual production volume is less than 25k parts, then you’ll likely want a prototype quality tool. In contrast, if you’re looking at +1 million parts, you’ll want to upgrade into production tooling to avoid doubling down on your mold investment.

Another great point is building the mold with the right materials and features. When we talk about steel materials, we look at the chosen material’s physical and chemical properties. You don’t want a glass-filled material running thousands of shots in an aluminum mold because it will wear faster. With mold features, you can underestimate the labor cost of a mold with multiple hand loads and other manual-intensive features.

Plastics Plus manufactures all its tools to SPI specifications. And because any tooling built and retained is maintained at no cost to the customer, it is in both of our interests to conduct a full risk analysis and mitigate any risks before turning on the build.

4: Labor

Labor might not strike you as a risk factor. But the truth is – labor can be sneaky and costly when unaccounted for. There are a few circumstances where we try and address any labor risks, so let’s dive a bit deeper.

Part and Tool Design: good manufacturing design principles will tell you that fewer components in any given assembly are ideal for manufacturing. How does this relate to labor? Well first, more components will require more labor-intensive activity like degating, deburring, trimming, machining, welding, and more. This introduces the possibility of variation and mistakes in handling the product.

Then, we must consider the risk with the actual assembly of the product. The further along down the production lifecycle, the more valuable the product is and the more expensive it is to lose on defective parts. Ultimately, we look at the risk associated with performing the entire assembly along with the possibility of not having enough people to do them. This is especially an issue with the current labor shortage.

For tool design, we look at whether the tool is automatic or not. The question we ask is “does an operator need to stand in front of the machine to do XYZ”. If not, then the machine can run without operator supervision (aka does not use labor resources). If the mold has multiple features, like hand-loaded inserts, then that requires much more labor.

Physical Injury: Good Manufacturing Practices (GMPs) and OSHA standards cover most common workplace accidents, and we value injury prevention as much as any manufacturer. But as we mentioned above there are inherent injury risks present with labor. And the injury doesn’t always happen at work. An injury can occur on the factory floor, or it can occur outside of work during a pickup game at the YMCA. Either way, injuries are a risk we must consider as it contributes to a strained workforce.

*Just a note: we rotate positions on our production floor for this reason. It’s unlikely someone will sustain a serious injury, but it’s a risk that is still present.

5: Equipment

Equipment failure isn’t something we run into often. However, the inherent risk with unplanned downtime due to equipment failure must be considered in the risk assessment. Unplanned downtime due to machine failure or mold damage happens for a few reasons: One – the equipment runs past its expected lifetime and requires repair or replacement. Two – the machine does not function as intended because of numerous factors. To prevent the latter, we test and validate our processing procedures to reduce human-caused errors. Furthermore, we keep a detailed maintenance database to check the pulse on all our equipment.

Another risk we consider is sourcing a new piece of equipment. For example, a new project might require a minor investment in equipment such as a fixture. Another might require us to buy an entirely new piece of production equipment like a heater or dryer. In either circumstance, we are at the mercy of our supplier. If the lead time on that equipment is extensive that poses a huge risk to the project’s timeline. Under those circumstances, the cost due to lost time can result in thousands of dollars. Therefore, we do our due diligence to ensure that we receive and can operate the required equipment for your project.

6: Packaging

By working with Plastics Plus, you have the option to produce a finished, packaged product. In other words, your product can be molded, assembled, and packaged all under our roof and shipped to you ready for market. This is a great advantage for you as the product owner, but it doesn’t come without risk.

The risk in packaging is a combination of a few other risk areas that we’ve covered in this article. For example, let us examine the packaging equipment. A complex packaging machine can do a few things at once: unroll, print, open (with air), and seal the package within a single cycle. Any variation in this process will impact the quality of the packaging and potentially the product. And any machine failure will result in unplanned downtime. In either case, the result is a loss of time and money.

Now let’s look at this from a materials standpoint. As with most supply chain constraints, not being able to source the packaging is the primary risk. The secondary risk is sourcing poor-quality packaging that doesn’t meet either of our standards. If we added a third risk, it would be scrapped packaging. All three of these situations pose a risk to our operations. But more importantly, it poses a risk to your bottom line which is what we are aiming to improve in the first place. Before we jump into one more area of packaging risk, we should remind you that our quality system is designed to prevent the poor product from ever reaching your doorstep. Thus, you can be confident will address any major concerns upfront.

No one likes to be blindsided by poor foresight.

Since we mentioned shipping to your doorstep, we should address the risk with shipping products. When we ship products via courier there are a few things that can happen. For instance, products on long-hauls can be damaged on their route because of poor handling. Nevertheless, we contract with major courier services to ensure that a professional is handling the product. Ultimately, the risk here is minimal but needs to be considered as part of our process.

7: Application

Application, or the end-use of the product, is one of the most important portions of our risk assessment process. We need to collect as much information on the use of the product and the environment as possible. During our initial conversations, we will expect to learn exactly who the end-user is and what the impact of the product is. Furthermore, we will want to identify the level of safety (or danger) for the user. On a similar note, we will consider whether the product is fit to function in its intended application.

For example, products that come into direct contact with a medical patient (such as a cannula) carry a higher risk factor than a plastic clip. Similarly, if the component is critical to the operation of an assembly or device (such as a CPAP) then the risk is also high.

Comparatively, if the product does not interface with the user and has low criticality then the risk factor is lower. Nevertheless, we still evaluate whether the product can be successful in its normal operating environment. Just because the risk for injury or death is low, we still want to prevent product failures. In this case, we’ll look at the fit and function of the part from an engineering and materials standpoint to identify any red flags. Ultimately, it is your job to determine whether the product is fit for purpose.

For review, we covered three application risks in this section:

Risk to the user
Risk of criticality
Risk of fit for purpose

Next, we’ll cover risks associated with compliance and quality requirements.

8: Regulatory Compliance

Regulatory compliance isn’t necessarily a risky undertaking for most projects. FDA compliance, GMPs, and other regulatory/ statutory requirements are handled primarily on your end. But we often abide by the same requirements to give our customers a seamless experience. However, these requirements prove to be more stringent for some products than others. Some of these falls outside of our capabilities, namely controlled molding environments and ISO-certified clean rooms. Under those circumstances, we avoid risk by turning the project away. On the other hand, we assess projects within our capabilities and determine the risk of falling out of compliance. All things considered, our quality department ensures that our party abides by all requirements laid out by you, the customer.

9: Special Quality Requirements

Validation is a staple in any robust Quality Management System (QMS). This is a multi-step, cross-departmental function in most manufacturing companies. It proves the capability of the methods machinery used to produce, measure, and test the manufacturing outcomes. In other words, the quality requirements set forth by the customer are fulfilled through validation procedures.

When we consider the risk inherent in those quality requirements, we look at the capabilities of our staff, equipment, and processes. These risks are like those present with regulatory compliance in that every product is a bit different. The first thing to consider is whether we can meet the proposed quality requirements. Some products carry tight tolerances in their drawings, critical dimensions that are unavoidable. Although we specialize in close-tolerance injection molding, we encounter some dimensions that are outside our capabilities. Once we establish competency to meet those requirements then we show our proof in the pudding. Explicitly, we’ll run our tests (IQ, OQ, PQ) and conduct others as required (PPAP, MSA, DOE, etc.).

If you want more information about our quality procedures, you can follow the link here.

Conclusion

By now, you should have a grasp of all the elements of proper risk assessment. Congratulations! You’re on your way towards approaching risk like a seasoned pro.

Good luck with your next project! Contact us if you need help conducting a full risk assessment on your next injection molding project.

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What is the question burning in the back of the mind of manufacturers today? The same as it’s been for decades – how do I reduce my costs and increase productivity? With the mix of labor force struggles, high demand for products, and strained supply chains, maximizing efficiency is more important than ever. That is because time is a limited resource and already spread thin in most factories. So, how can we maximize our use of time to bring costs down and produce more? One way is to design an efficient assembly process with a one-piece flow.

In this post, we will introduce the concept of one-piece flow assembly lines. We will discuss why this process is more efficient compared to other assembly processes. For example, we will focus on the difference between batching and one-piece flow. Additionally, we will link to a video that illustrates how much time you can save with this process.

Ready. Set. Assemble!

What is One-Piece Flow?

Flow is the movement of a product from one operation to the next in a value stream. With a one-piece flow, the goal is to plan the workflow based on the products’ needs while eliminating wasted movements. In other words, with the one-piece flow, you want to cut touches that interrupt workflow and that aren’t value-added. Ultimately, this allows you to move between operations without work-in-process (WIP) between them.

To demonstrate, some real-world examples of continuous flow are flowing water and wind. These two elements flow continuously until they are restricted by obstacles (rocks, trees, structures), constricting their flow. Below is an illustration of this happening in nature.

As you can see from the illustration, the canoes can travel down the river with ease when there aren’t any obstacles. When we introduce objects that interrupt that flow our adventurers have a much harder time traveling downstream.

Continuous flow in nature This is a canoe on a river with interrupted flow

Bottlenecks:

On the production line, this creates what we know as a bottleneck. A bottleneck is a process in an assembly line with limited capacity that affects the capacity of the entire line. In other words, a bottleneck constraint occurs when there is too much work/ supply at a specific point in a process. Ultimately, a bottleneck holds up the rest of the operation up and down the value stream. This results in longer delays and higher production costs.

Where Did One-Piece Flow Originate?

Single-piece flow comes from the lean manufacturing practice of just-in-time (JIT). The well-known car manufacturer- Toyota -pioneered this idea in the mid 20th century. With just-in-time, manufacturers produced components only as needed and nothing more. In other words, with a one-piece flow, the manufacturer delivered a product only when the customer demanded one.

This lean system resulted in many manufacturing revelations. For one, it helped standardize many processes and workflows. But more importantly, one-piece flow helped cut inventory build-up and cost. Because of this, manufacturers were able to fill orders at the rate of customer demand without having to back stock pallets of products. All in all, by optimizing their workflow manufactures reduced their inventory cost, used time and resources more efficiently, and increased their output.

Why is One-Piece Flow Better Than Batching?

Batching is the process of finishing one operation for a whole batch of pieces before moving on to the next step. For example, for a batch of 10 parts, an operator would complete step 1 for all 10 parts before moving onto the next step. Most of those unfamiliar with lean manufacturing would accept this as common sense and run with it. Some would even argue that it is an efficient method.

Not so fast!

What happens with batch processing is this massive pile-up of inventory between each station. We know this as work-in-process (WIP). And when there is WIP someone is waiting for that process to finish. That someone could be the next person on the line, or a customer waiting for their product.

Waiting time = wasted time.

Check out this illustration showing the time-saving between one-piece vs batch processing:

Batch Processing Single-piece flow graphics

In this example, when we use single piece flow we reduce the assembly time by 40%!

Let’s break down what we are seeing above in batch processing:

Operator 1 (Blue) has to complete Step 1 for all 10 parts in the batch. She then passes all 10 pieces to the next operator.

Operator 2 (Orange) gets her hands on the batch after patiently waiting. Now, she must complete Step 2 for all 10 pieces. There are now 10 parts that are WIP. * Side note- If this operation were to continue past these 10 parts there would actually be 20 parts in WIP and 30 in the next step.

Finally, Operator 3 (Green) initiates Step 3. After the first 60 second cycle, we finally have 1 finished good. But, it has taken us 21 minutes to complete just 1 part! At the end of this operation, they will have spent 30 minutes on these 10 parts.

Now, let’s move over to the single-piece processing graphic:

Operator 1 (Blue) takes one piece and completes step 1 in 60 seconds. She moves the finished part to the next operator and grabs a new part. She’s moving fast!

Operator 2 (Orange) ‘pulls’ the first part to her station and finishes her step in 60 seconds. Again, she moves the part onto the next station and pulls a new piece. We’re on a roll now!

Operator 3 (Green) now has the first piece. There are a total of 3 pieces that are WIP and 7 that have yet to be touched. But, once this step is completed they will have completed their first finished good in 3 minutes! Also, they will now churn out a finished good every 60 seconds because there is a continuous flow. After just 12 minutes, the second line has finished their batch of 10 parts.

See the difference? If this wasn’t clear enough, check out this animation.

Now that you know what you (might) be missing out on, we’ll show you how to set up your workstations for one-piece flow.

How To Achieve Continuous Flow

Yes, the one-piece flow has many advantages. Yet, to implement this process you need to meet certain requirements. Without these requirements, the one-piece flow will be near impossible to achieve.

Here are those requirements:

Maintain 100% machine uptime (or as close to 100% as possible).
Work, resources, and time must be divided evenly amongst workstations.
Work-in-process (WIP) must be limited to one item in any station’s queue.
Time to complete a task must be measurable and repeatable.
Time to make one-piece must be scalable to customer demands (takt time).
The quality of resources must be consistent. Inconsistent quality equals poor defect rate.
The operation must be able to consistently produce good results.

Variation is the enemy of continuous flow. To achieve an efficient flow, you have to cut variation from the process. If these conditions above aren’t met, then ultimately you will not achieve a one-piece flow down your value stream. After all, it is possible that your product is not suitable for one-piece flow.

But if you do have what it takes to kick the variation bug, then here are the 6-steps to creating your own continuous flow workstations

6 Steps For Creating Continuous Flow Workstations

Step 1: Design a connected flow

A connected flow involves linking each process step within a value stream. In other words, you can establish an underlying relationship between each processing step in a connected flow. Each manufacturing step is either directly related, or related by a pull system like FIFO. Ultimately, the goal of this relationship is to move the product from step to step with little to zero waiting time.

Step 2: Determine whether the workstation is product-focused or mixed

Basically, the difference between product-focused and mixed is the number of products that occupy that workstation. For instance, if the workstation focuses on one product then you can focus on that process. However, the demand for this product must be high enough to maintain a continuous flow.

If there is a mix of products that need assembly at this workstation, then the rules change a bit. For example, if the workstation has to accommodate product A one hour and product B the next, you’ll need to use a mixed station. With a mixed station, the goal is to minimize changeover time. Changeover time is the time between the last good product run and the first good product of the new run. As a general rule, changeover time must be less than one takt time.

Step 3: Calculate Takt Time

Takt time– a measurement of customer demand expressed in units of time. Takt time allows you to keep a pulse on your customers’ demands without under or over-producing products. This is another concept of lean manufacturing and just-in-time where the customer only receives a product when they ask for one. Ultimately, this drives production and inventory costs down.

To calculate takt time use the following formula:

Takt time= Available work-time per shift / Customer demand per shift

Step 4: Determine the processes and time required for making one piece

Step 4 involves conducting an extensive time study on each of the individual processes within the whole operation. First, you need to identify each step in the assembly process from start to finish. Then, you will want to follow a single product through the process from start to finish. Record the time it takes to complete each step as you move through the process. Once you finish, go back through and time each step repeatedly. From this data, take the lowest repeatable timestamp and use it as your baseline going forward.

Can your recorded times match up to meet takt time? If not, you may need to reevaluate your processes and/or equipment.

Linkable content – How to conduct a time-study.

Step 5: Create a lean layout using elements of 5-S

Creating a lean layout is a difficult, but necessary activity. The goal at this stage is to limit wasted movements within the work cell. For example, placing equipment and material at the point of use is a great way to cut wasted movement. On the other hand, if the operator must turn around every 5 seconds to grab a tool then they are wasting movements. In short, wasted movement slows down the line which creates more WIP- a cardinal sin in this discipline.

Another great way to cut waste is through the workstation’s design. The most common design, and perhaps the best, is the U-shaped workstation. This gives an operator full access to resources with limited movements. Yet, there are some instances where a U-shape is not possible due to space constraints. You can experiment with other shapes to find out the best for your situation.

Linkable content: Case Study- Why the popular video game Overcooked is a perfect example of bad cell design.

Linkable content: What is the 5-S methodology

Step 6: Balance the workstation and create standardized work instructions.

The last step is to balance the workstation and deploy a standardized process for splitting up the work time. For example, our earlier segment showed a 3-step setup with each step requiring 60 seconds of work-time. The entire process takes 3 minutes to complete, which can be split up between 3 operators for balance. If we added an operator, then we would split the time amongst the 4 – equalling 45 seconds each. Similarly, we can subtract an operator and split the 3 minutes in half, 90 seconds each.

Again, the way to balance the cells depends on the number of steps and how much time each step needs. There is a formula that tells you how many operators you’ll need to be successful. That formula is shown below:

Number of operators = Total work content/ Takt time

Ex: 720 seconds / (28800 seconds in a shift / 100 parts per shift demanded)= 2.5 operators

Oops! We have half an operator leftover! This is called an inconvenient remainder. With these remaining operators, it is difficult to balance the assembly line. You can reallocate these operators/ activities to resource management to balance the line. Or, you can reevaluate your value stream to make it more efficient. To do this you need to cut steps out of the operation or reduce the time needed to complete the longer steps.

In conclusion, one-piece flow is one of many ways to optimize an operation. Most of the time, continuous flow is achievable with one, if not all value streams. But, that is if you have the right resources. If not, then it is important to continuously improve processes to try and achieve this flow. Ultimately, this is the way manufacturers can increase output, reduce costs, and keep customers stocked. If you don’t have the resources, for whatever reason, then working with a contract manufacturer would be the best course of action.

Plastic manufacturing is a popular subject that appears across every industry. From food processing to automotive components, plastic is a staple of the products we use. It’s in our packaging, our transportation, our clothes…it’s everywhere! To meet the high demand for plastic, manufacturers leverage different types of processing capabilities. This includes blow molding, compression, extrusion, rotational, 3D printing, and injection molding. Each one of these methods is capable of producing a specific plastic application. For example, blow molding is best for making plastic bottles, and extrusion is best for tubes. Our service, injection molding, is perfect for mass-producing plastic components.

We’ll discuss these different plastic manufacturing methods in depth throughout this segment. Follow along, or skip to one of the methods of your choice.

What is Injection Molding?

Plastic injection molding is a popular method of making a variety of plastic parts. This process involves melting thermoplastic material through an injection molding machine. First, plastic resin enters the machine via the hopper and enters the barrel. The barrel contains a reciprocating screw, which mixes and melts the plastic. Then, the press injects the molten plastic into a single or multi-cavity mold. The mold clamps shut during injection and open at the end of the cycle. Finally, the cooled part falls from the press and is handled by a machine or an operator.

This is an oversimplified explanation of course, but the capabilities of molding are easy to illustrate. For example, this cycle happens (in most cases) under a minute and sometimes even under 20 seconds. Pair that speed with a multi-cavity mold and you can make thousands of parts a day. Ultimately, this means you can take advantage and scale production quickly.

To wrap up this section (because I could go on) injection molding is fast, scalable, but also repeatable and versatile. The results of injection molding are consistent from run to run, which means you can expect a certain level of quality. And it is versatile because you can make complex 3D shapes. Of course, you have to optimize your design for manufacturability and assembly for it to be moldable. But, if that is taken care of then the possibilities are limitless.

Ultimately, injection molding is best for high-volume production. Whether that application is a medical device, automotive component, or bottle caps; you can produce lightweight, strong plastic parts.

What is Rotational Molding?

Rotomolding is similar in the way that it utilizes a mold to force the plastic to take the desired shape. Except in rotational molding, the polymer is a fine powder that fills the mold. The mold is placed on a rotating arm that operates by moving on a 3-dimensional axis, which helps fill the mold. The mold, while in rotation, enters into an oven that produces heat between 400 and 500 degrees Fahrenheit. The oven encloses the mold for the necessary duration, then moves to a cooling phase. The mold cools under specific conditions dictated by the material and size of the mold.

Rotational molding is a low-pressure manufacturing process. This means that the tooling requirements aren’t as much as other methods, which reduces the cost. For instance, a thin-walled aluminum mold is much less expensive than heat-treated stainless steel used in injection molding. Additionally, there is an opportunity to ‘foam’ rotomolded parts. This means that you can add insulation, floatation, and other capabilities to your product.

Rotational molding is considered a versatile process when it comes to plastic manufacturing. But Rotomolded parts are typically bigger, less precise units that are machined for functionality. So if you want a large plastic unit, like a play structure or a large drum container, rotational molding may be right for you.

What is Blow Molding?

Water bottles in a blow molding plant

As explained in the introduction, blow molding is great for making plastic bottles. But how does it work? Well, it’s actually like glass blowing but with plastic. You start with a small plastic parison- a rounded mass formed by heating and rolling- and blow gas (air) through it to inflate. Essentially, the small plastic mass inflates according to the shape and size of the mold. Once it cools, the inflated part ejects from the mold.

Blow molding is great for manufacturing one-piece, hollow plastic objects. Like soda bottles! It is also useful for thin-walled applications like plastic storage containers. Like injection molding, blow molding produces high volumes because of its quick cycles. Additionally, there are many thermoplastic materials that are compatible with this process. This creates plenty of opportunities to create specialized products.

What is Compression Molding?

Compression molding is another popular molding method used by automotive part makers. The process is like injection molding, except the mold closes around the plastic during compression. For illustration, the plastic ‘charge is set on the bottom half of the mold. Then, when the press starts the top half smushes the charge into the cavity. The plastic fills the cavity and seeps out into overflow grooves. This is like the runner and gate in injection molding.

Another key difference is that compression molding uses thermoset polymers. This means that after molding, the resulting component must ‘cure’ in a kiln-like oven. Through curing, the component settles into and holds its finished shape.

There are 4 main steps to compression molding:

A two-part metallic tool matching the exact dimensions of the object is produced, installed, and heated to the requirements of the plastic.
The plastic composite is pre-formed to the shape of the tool.
Under pressure, the pre-formed object is inserted in the hot mold and compressed. This pressure ranges anywhere between 800 psi and 2000 psi depending on the thickness of the part.
The part is removed from the tool and any flash on the edge is trimmed off.

The main benefit of compression molding is the ability to use advanced composite materials. These materials include thermosetting resins, glass-reinforced plastics, fiberglass, and other strong materials. With these materials, you can create a wide range of parts for a variety of applications. Also, with compression molding, you can create simple and somewhat complex geometric shapes. To summarize, compression molding is versatile enough for many low and medium-volume production projects.

What is Extrusion Molding?

The initial process of extrusion molding resembles that of injection molding. The extrusion press uses a screw to melt and push plastic resin through the die. A die, unlike a mold, is a hollow form that shapes the plastic as the screw pushes it through. In other words, the die dictates the specific shape and thickness of the manufactured part. The extruded part is then conveyed into a cooling chamber- a water bath or spray booth. At the end of the cycle, a saw or blade cuts the long extruded material in sections of the desired length.

One key feature of extrusion molding is its continuous process. For example, the extrusion press continuously feeds plastic through the die. This creates a long beam or tube of molded plastic that stays intact until it is cut or wound into a spool. If you haven’t picked up on it yet, extrusion molding is great for long, hollow applications. For example, tubes, straws, pipes, and wires are also extruded applications. Also, channel sections are a popular extruded product as well.

What is Additive Manufacturing (3D Printing)

Additive manufacturing is better known as 3D printing. And it is all the rage in the 21st century. 3D printing uses CAD software and 3D object scanners to program hardware (such as a printer) to make an object. In other words, the digital software recreates an object digitally; which tells the hardware how to physically make it in layers. The 3D printer then produces super-fine layers of material in precise geometric patterns. Layer by layer, the printer deposits material until the final product takes form. This can take minutes, hours, or days depending on the object. But, additive manufacturing is still considered an easier way to develop and test prototype products.

While the technology is advancing, additive manufacturing is still behind in volume capabilities. But, as hinted above, you can skip the wait and test prototypes quicker than other molding processes. For example, with injection molding, you would have to spend thousands of dollars to produce a prototype tool. Not only is that expensive, but the lead times on a tool can set your schedule back. Plus, if for any reason the product is redesigned then that is another costly headache. With 3D printing, you can develop and test prototypes in weeks, not months.

Wrap Up

Now you know the basics of plastic manufacturing! There are a lot more details once you go further into one of these processes. Don’t be discouraged though! There are experts in each of these fields that can help you and understand your challenges. If you’re looking for an injection molder then give us a call!

Injection molding is a common process for making plastic products in large volumes. Most people that are familiar with the subject know its capabilities.

Those same people also know another aspect of injection molding: the cost of building a mold.

The capital investment with building a new tool is a challenge for buyers and engineers. This investment checks out in the tens of thousands or even hundreds of thousands of dollars. A sum like this causes friction for launching new products to market, where the product has yet to be tested. Additionally, a project that is still testing the market won’t have a clear ROI forecast. Because of this, many teams are hesitant to invest in a tool without proof in the pudding.

Luckily, injection molders provide options for teams in different stages of their project. One of these options is to select a class of tools that matches your needs. For example, there are three types of tooling: prototype, bridge, and production. Each type of tooling has its benefits and disadvantages. But, each type will offer results at a reasonable price. Let’s jump into these tooling options further.

Prototype Tooling

Defining ‘prototype tool’

A prototype tool, also known as a Class 5 tool, is a low-volume run tool made for products that are in the development and testing stage. This class of tooling is great for testing a design’s functionality while staying flexible with design changes. Because of this, prototype tooling is a great starting place for rolling out new to market products.

Prototype tooling costs

The upfront investment in tooling is the biggest barrier to injection molding. Production-ready tooling is often too much for projects that are new and unproven. In comparison, prototype tooling is by far the lowest-cost option. Because of this, many companies choose to build a prototype tool first and then test their design. By doing this, companies will identify issues early and correct them on production-level tools. This will help cut costs at the earliest value stages of the project.

Types of Steel Used in Prototype Tooling

One of the key differences between tooling types is the kind of steel used in the mold build. When building the mold, a toolmaker can choose from a few different steel types. Each of those options will affect how long the tool lasts, how well it performs, how expensive it is, and what features the tool can use. Additionally, every type of steel has its own core properties. For a prototype tool, the mold base is made of low to mild-grade steel or aluminum.

Key Features of a Prototype Tool

Prototype tooling is a no-frill, but cost-effective way to get parts made and onto the market. Because of their simple configurations, a prototype tool uses cut-in-steel cores and cavities. This means that the toolmaker will cut the cavity/ core into the mold block itself instead of making interchangeable cavities. Additionally, class 5 tools will often opt out of expensive features: like complex cooling channels, runner systems, slides, and other features found on production tooling.

Takeaways from Prototype Tooling

+ Cost-effective

+ Great performance for the price

+ Standard textures and polishes

+ Great for testing features/ fit for applications

+ Flexible designs

+ Great for testing market demand and project ROI

– Low volume

– A short lifespan (>500shots)

– Minimal features

– Soft steel (easy to damage)

– Not weldable

Bridge Tooling

Bridge tooling is the intermediate step between prototype and production tooling. As the name suggests, this type of tool is a stopgap for products that have succeeded in their early stages. As a result, these products are ready for higher volume production. And with high volumes comes the need to upgrade your tooling.

However, bridge tooling is limited when compared to production tooling. For example, a bridge tool is not equipped with advanced features- like complex cooling channels. But, by choosing not to have these features you can cut significant costs. For this reason, bridge tooling is great for dialing in the process, calculating ROI on the project, and testing the market.

When should you use bridge tooling? And when is it appropriate to use full-production tooling? The answer to this depends on several factors. For instance, we look at the product’s application, the expected volumes, the material used, and more.

Mold Base and Tool Life

The steel used in a bridge tool is dependent on how many lifetime shots you expect to get out of the tool. For a Class 4 tool, the base can be made out of mild steel material. This will get you up to 100,000 shots/cycles. For a Class 3 tool, you will have to spend more to get hardened steel (minimum of 165 BNH). However, with this tool, you can expect to get 5 times the amount of shots (500,000).

Material Hardness (Resin Choice):

Material choice is an important factor in deciding what grade steel to use. For a bridge tool, a harder resin will wear the tool down faster. This will affect the life expectancy of the tool. Additionally, if the tool closes on a rigid plastic part, it could damage the mold. These damages aren’t dramatic, but the cost of maintenance and potential downtime increases.

Application- How it’s used:

The product’s environment and function influence the volume and material. First, if the parts are high in demand and replaced often, then you can expect high volume production. Second, if the parts are often exposed to harsh environments- chemicals, heat, etc… then you will need rigid material. With the combination of rigid material and high volume, it is best to consider hardened steel.

Production Tooling

Think you’re ready for production tooling? Great! There are many reasons to build a production-ready tool. One of the main reasons: dependability. A hardened steel tool is reliable and can make hundreds of thousands of parts. Thus, these tools make great ‘flagship products’- your main product offering.

Mold Base and Tool Life

Class 1 and Class 2 tooling are your best options for high-volume production runs. All Class 2 molding services (cavities and cores) are made of 280 BHN hardened stainless steel. Additionally, this steel is heat-treated to a minimum of 48 Rockwell “C”. This hardness allows the tool to last up to 1 MILLION cycles.

A Class 1 tool will get you into the multi-million cycle mark for extreme volume projects. This type of tool also has a minimum hardness of 280 BHN but is heat-treated to 48 Rockwell “C”.

Summary of choosing the right tool for your needs.

Ultimately, a high-end car is better than a low-end car, but there are reasons to hold off on the big price tag. The same applies to an injection molding tool. A production-capable tool may have all the bells and whistles. Yet, the cost of hardened steel and complex fixtures may surpass the needs of your project.

Ultimately, the type of tool you need depends on where you’re at in your project’s lifecycle. If you’re launching into a brand new project or one you haven’t tested the market for, build a bridge tool.

If the design you have may go through many revisions before it goes on the market, build a prototype tool.

If you have the next best product on the market, and you’re selling quantities of 500k or more, splurge on a production tool.

Looking for contract manufacturing?

When it comes to manufacturing there are two ways of doing it:

Roll up your sleeves and do it yourself.
Find someone who knows how to do it well and have them do it for you.

The first option is empowering. You have complete control over the process, quality, and the ultimate outcome. In the same way, you can run around your house fixing any problems that arise with some elbow grease and a tool belt. You would have complete control to make repairs how you want.

Except manufacturing isn’t all that simple. And instead of elbow grease, you will need an army of elbow greasers with an immense level of expertise. Not only that, but you will also need to buy a house (manufacturing plant) and very expensive machinery to get the work done.

This is a big undertaking. Especially for businesses that focus on scaling their business through sales and marketing. That is why working with a contract manufacturer is SO valuable! A contract manufacturer gives you access to valuable resources at a fraction of the cost.

After reading this article you will understand what a contract manufacturer is and what a partnership includes. Finally, we’ll show you how to select one that fits your needs.

What is Contract Manufacturing?

Contract manufacturing is the process of outsourcing your production requirements to a facility that is better equipped to fulfill them. In other words, a manufacturer is hired to make products or do other labor for the hiring company. In most cases, the manufacturer produces a set amount of products within a given period of time.

How does contract manufacturing work?

First, the contract manufacturer approves all the job requirements. Then it will perform the job based on the contractual agreement. This includes approving the design, material, processes, shipping requirements, and more.

The contract manufacturer does not own any intellectual properties that it is producing. No, the hiring company owns most, if not all the IP. This includes drawings, processes, work instructions, packaging, and more. In fact, many contract manufacturers make products EXACTLY to their customers’ specifications. These are build-to-print services. There are also build-to-spec services, but that won’t be covered in this writing.

The contractual agreement can extend for a long period of time. This gives the hiring company the ability to order products on demand from the manufacturer. To receive more products, the company places an order and specifies a date they need it delivered by. The contract manufacturer then pulls together the necessary materials and starts producing parts. Once good products are available, quality will inspect the parts and send samples. Once approved, production can continue until the order is complete. This process repeats until the agreement is either completed or terminated.

Learn more about the resources you need to pull together before starting production.

What types of contract manufacturers exist?

There are many niches that leverage the services of a contract manufacturer. As a rule of thumb, most contract manufacturers are exporters or converters of raw materials, machinists, or assemblers. For example, we are a plastic injection molding company. We convert raw plastic material to produce plastic components. These are used in applications for medical devices, automotive, and mission-critical operations. Our specialty is in plastic materials and processing. And we also offer machining, assembly, and other services as secondary ops.

For a better overview, check out this list of contract manufacturing examples:

Raw materials processor (rubber, plastic, steel)
Die casting/ mold building
Machining (CNC, milling, grinding)
Stamping
Foundry model (for semiconductors and electronics)

Why is contract manufacturing important?

Contract manufacturing is important because it provides the ability to perform full-scale production that would otherwise be impossible without capital-intensive investments.

Manufacturing requires expertise, a skilled labor force, accessible resources, quality control, supply-chain management, and more. Even then manufacturers themselves can’t produce everything they need. With a contract manufacturer, a company has access to the necessary resources that would be otherwise near impossible to get. With access to these resources, they can focus their strengths on their customers’ needs.

What Work does Contract Manufacturing Include?

First, you need to pinpoint what work you’re hiring for. For example, if you’re hiring a sub-component manufacturer then the scope of work will be different than an assembler. But, if you hire a comprehensive manufacturer you will have more options to choose from.

Generally, there are a few important assets included in working with contract manufacturers. These assets are the main selling points for why you need a manufacturing partner:

Facility and Equipment

The facility and equipment cost is a huge factor in outsourcing decisions. With contract manufacturing, you are essentially leasing the space and equipment owned by them. This is less expensive and causes much fewer headaches.

Labor

We are talking about two kinds of labor forces: skilled and unskilled labor.

Unskilled labor– This labor force includes machine operators, assemblers, heavy-lifters, and others. They are often underappreciated, but super valuable members of the team. These people handle raw materials, finished goods, and make sure your products are taken care of. Ultimately these workers aren’t expensive but are an essential part of the puzzle.

Skilled labor– Skilled labor refers to those who deploy knowledge, expertise, or a rare and valuable skill in their work. This includes engineers, processors, machinists, material experts, and more. These workers are fewer in numbers but contribute more value. Additionally, these experts are more difficult to find the more specialized they are. This makes it harder to bring their expertise in-house for your own processes. But, they work for manufacturers in their respective vertices. Which makes them accessible as part of the partnership.

Sub-components

While some companies are makers of one-piece products, others make multi-part assemblies. These multiple parts, or sub-components, are a part of a large device as a whole. Many companies will contract a manufacturer to produce these sub-components so that they don’t have to produce every part in-house. They will even ask to produce multiple parts, assemble them, and ship them as a finished good.

Full-Scale Production

This allows businesses to contract out many production activities down the supply chain. For instance, in the automotive industry, there are three-tiers of suppliers:

Original Equipment Manufacturer (OEM) – An OEM is the label company that is often designing, marketing, and selling the car. These manufacturers make some original parts but engage more in ordering parts and assembling the final car. They order parts from their 3-tier suppliers.

Tier 1– Tier 1 suppliers are the direct suppliers to the OEM. This tier of companies works with multiple car manufacturers. But, they have some exclusivity with one or two OEMs.

Tier 2– Tier 2 suppliers also make car parts in this example. Yet, these companies usually don’t sell directly to OEMs. Instead, Tier 2 suppliers sell to Tier 1 who then distributes that along their channels. Another difference is that Tier 2 suppliers are not industry-specific. In other words, while some do make automotive parts, they can also serve other industries. Tier 2 suppliers are experts in their niches and have a broader capacity for serving different markets.

Tier 3– Tier 3 suppliers are suppliers of raw materials, like plastic and metal. Each of the tiers above is dependent on this one. Because of this, Tier 3 has a great responsibility within the manufacturing supply chain.

To summarize this section, contract manufacturing can be distributed amongst the three theirs. In fact, this allows for greater supply-chain visibility and flexibility.

When Should I Start Considering Contract Manufacturing?

If you’re reading this right now and salivating at the idea of contract manufacturing, then you’re ready. If you’re not sure yet, then that’s fine too! Ultimately, you must look internally at your own capabilities to determine if it’s right for your business.

In our experience, companies who fit the bill for contract manufacturing:

Have limited resources (equipment, labor, process, expertise)
Are already stretched thin (limited bandwidth)
Want to focus on their current strengths
Have a complex supply-chain
Have variable demand for their products

How do I choose a contract manufacturer?

There are many factors that go into choosing a contract manufacturer.

The most important- find one that you trust will have your back and can do the job right.

You can find hints about how a manufacturer conducts business with some thorough research. Most contract manufacturers have a way of conveying their capabilities for your specific needs. Others will have references, work history, or verified qualifications that prove they can meet those needs.

Here are the top 5 things we recommend taking a look at when comparing contract manufacturers:

Certifications:

Most manufacturers that are well established have ISO-certified quality management systems (QMS). If not, then the company would need further investigation or should be removed from your list. ISO certification from a third party demonstrates the manufacturer’s commitment to quality. Plus, some certifications cover industry-specific requirements that need to be met. This should give you more confidence in their ability and results.

2. Examples/ history of working in your industry

The point of contract manufacturing is to relieve your business of extra work, not add more. Thus, a manufacturer with experience in your industry can help you solve problems and speak your language. Without this quality, you will spend more time asking questions than solving problems. Look for one that has experience within your industry, or has similar capabilities.

3. Excellent Referrals

Manufacturing is a business that thrives on referrals. If someone had a great experience working with a contract manufacturer, then they’ll tell you.

If not, they will also tell you.

Most companies keep supplier scorecards that show performance over time for that manufacturer. Other sources include reviews, verified partner badges, group affiliations, and similar third-party verifications.

4. Good labor practices

This one is harder to test but is a crucial piece of the puzzle. You will find that some manufacturers aren’t transparent about their labor. This could be a sign of trouble. A poor work environment affects the quality of their work, aka your product. And if they don’t treat workers well, how do you think they treat customers? I’ll let that go unanswered.

5. Supply-chain network

As I’ve stated a few times, the supply chain is crucial. You want a partner with a steady network of suppliers who can activate when needed. Long lead times, late deliveries, defect parts are all things you want to avoid right? These hiccups cost your business money, so avoid them with a well-tied supply chain partner.

What Are the Benefits of Contract Manufacturing?

When working with contract manufacturers, you are reaping a ton of benefits. But, those benefits don’t come without some risks as well. Here we will break down some positives and negatives when outsourcing your manufacturing.

Advantages of contract manufacturing:

Cost savings
Scalable production
Flexible manufacturing solutions
Increased Quality
Repeatable outcomes

Disadvantages of contract manufacturing:

NONE… Just kidding, there are a few:

Stolen intellectual properties (IP)
Bad fit for service
Unreliable and potential for poor customer service
Less control over the outcomes
Disagreements over terms, partnerships, etc…

Final Notes

In summary, contract manufacturing is a great service that can help your business scale. For businesses that lack manufacturing resources, I would highly recommend finding a contract manufacturer to work with. Finally, if you have any questions about the process or you would like to learn more about our service then give us a call!