7 Common Elements Caught in the Design for Manufacturing Process

Getting products to market fast and on budget are two critical factors in the manufacturing process. The design for manufacturing process is cited by both product manufacturers and injection molders as the step that can have the greatest impact on production outcomes. When plastic injection molders are involved early in the part design process including prototype development and mold flow analysis, many cost and time efficiencies will be realized.

Designing a plastic part for manufacturability from the outset involves several considerations that can ultimately have a significant impact on key variables. While some manufacturers don’t account for design adjustments in their timelines, early collaboration with your molder may uncover aspects of a design that can be optimized to improve the efficiency of part production and performance. Here are a few of the most common elements caught in the design for manufacturing process:

1. Draft

As an essential requirement in injection molding, draft angles make it easier for a finished, cooled part to be released from a mold. Minimizing friction during the part release process is important to prevent damage to the parts, provide a uniform surface finish and reduce wear and tear on the mold.

Draft angles are calculated as a degree measurement from the direction of pull. Designing a part with sufficient draft is critical, which is why design engineers typically recommend minimum draft angles of 0.5 degrees for core and 1.0 degree for the cavity. More draft is also needed if a textured surface is desired and if there are steel shut off surfaces in the tool design.

2. Wall Thickness


Another important factor in part design is wall thickness. A proper and uniform wall thickness reduces the risk of structural and cosmetic defects in injection molded parts.

While typical wall thickness ranges from .04 – .150 for most resins, it is recommended that you work with a knowledgeable injection molder/design engineer to verify thickness specifications for the material(s) you are considering for your part.

Analyzing wall thickness is an essential step in the design process to avoid producing parts that have sink, warp or are ultimately non-functional.

3. Ribs

Ribs are used to strengthen the walls of your part without increasing wall thickness, making them a valuable element in injection molded parts. Particularly in complex parts, good rib design should shorten the mold flow length while ensuring the proper connection of ribs to enhance the strength of the part.

Since thickness and location are essential in rib design, ribs should be no greater than ⅔ of the wall thickness, depending on the material used. Using wider ribs may create design and sinking issues. To mitigate this, a design engineer will typically core out some of the material to reduce shrinking and maintain strength.

Rib length should not exceed 3 times the length of the wall thickness, as anything over this could lead to part shorting/not being able to fill the part completely. Identifying the proper placement, thickness and length of ribs in the early phases of part design is an important element to the viability of a part.

4. Gate Location


A gate is the location where molten plastic material flows into the mold part cavity. While every injection molded part has at least one gate, many parts are manufactured using several gates. Because gate location affects the orientation of the polymer molecules and how the part will shrink during the cooling process, gate location can either make or break your part design and functionality.

For example, if a part is long and narrow and must be absolutely straight, it is best to place the gate at the end of the part. For parts that need to be perfectly round, a centrally located gate is recommended.

Sharing preliminary part designs with your injection molding engineering team, leveraging their knowledge and expertise in material flow, will result in optimal gate placement and injection points.

5. Ejector Pin Location


After a plastic part is molded, ejector pins (located within the B-side/core of the mold) apply just the right amount of force required to eject the part from a mold. Ejector pin location is typically a relatively minor concern in the early phases of design, but marks and indentations can result from improperly placed ejector pins, which is why design and positioning should be considered as early as possible in the process.

The location of ejector pins depends on a number of factors, including draft and texture of sidewalls, depth of walls and ribs, and the type of material used. Reviewing part designs will either confirm that your initial ejector pin placement is correct or may generate further recommendations to improve production outcomes.

6. Sink Areas

When the material in the area of thicker features, such as ribs or bosses, shrinks more than the material in the adjacent wall, sink marks may result in the injection molded plastic part. This occurs because thicker areas cool at a slower rate than the thinner ones, and the different rates of cooling leave a depression on the adjacent wall that is commonly referred to as a sink mark.

Several factors contribute to sink mark formation, including the processing methods used, part geometry, material selection and tooling design. Depending on the part specifications, it may not be possible to adjust geometry and material selection, but there are many options available to eliminate sink areas.

Depending on the part and its final application, tooling design (e.g., cooling channel design, gate type and gate size) can be leveraged to influence sink. In addition, manipulating process conditions (e.g., packing pressure, packing time, length of packing phase and conditions) offers several options to reduce sink. Finally, minor tooling modifications, such as retrofittable components or process modifications (e.g., gas assist or foaming) are also available to combat sink. As a result, it is best to collaborate with your injection molder to determine which methods will work best to mitigate sink in your specific injection molded parts.

7. Parting Lines


Parting line location is worth noting and planning for when producing more complex parts and/or when complicated shapes are required.

Since part designers and molders tend to evaluate parts differently, sharing your design with your injection molder can dramatically affect the production and function of your finished product. If parting line challenges are found, there are several ways to address them.

Being aware of the significance of the parting line in your initial design is a good first step, but that may not be your only option. By leveraging CAD software and mold flow analysis, you may be able to determine other possible locations. Working with a knowledgeable injection molder will keep your part end use top of mind and will guide you to the best possible location for parting lines.

There is no question, engaging your plastic injection molder early in the design for manufacturability process and working closely with a design engineer to identify efficiencies will help get your product to market quicker and on budget. What challenges are you currently facing with the plastic part design process?

Learn how Nicolet Plastics can help you reduce lead times and identify turn-key solutions for every product.

6 Plastic Injection Molding Trends to Watch In 2018

According to Global Market Inc., the injection molded plastic market has established itself as one of the most dynamically evolving businesses in recent times. As one of the most commonly-used processes for product manufacturers, plastic injection molding is a precise method that can fabricate nearly any type of plastic part. Technologies, processes and materials used in injection molding continue to advance –  allowing manufacturers better insight to design, develop and produce the highest performing and cost efficient plastic parts.

Key areas that will continue to be of focus in the year ahead are the advancements in automation, sustainable practices, and software that allow for parts to be analyzed and tweaked virtually before production. In addition, industry experts credit lower oil prices, technological advances, technical expertise, and rapid growth in the building and construction sectors as drivers for continued future growth.

As we look ahead to 2018, we’re closely watching and leveraging the following plastic injection molding trends. Are you?

1. Automation

The impact of automation has been felt in virtually every industry, but the increased deployment of automated tools and robotics in the injection molding industry stands to be monumental. Automated robots boast speed, accuracy, agility and adaptability, which allows for significant increases in production.

Labor and energy make a tremendous impact on plastics processors businesses. To effectively compete internationally, processors must automate to increase the productivity and reduce costs of their operations in order to remain competitive.

Even when working with low to mid volume plastic parts, automation can greatly improve the cost and labor efficiency of production. However, automation is much more than simply adopting the use of robots. While automation may allow for increased processing time, a high level of skilled labor is still needed to manage operations effectively.

Another development in manufacturing automation, according to a recent report, is the integration of collaborative robots or “co-bots” which are increasingly being adopted to work collaboratively with humans. Through the use of robot controllers and specialized sensors for operations, manufacturers are able to address common issues such as labor shortages, repetitive processes and ergonomically-challenging tasks. In fact, many businesses that have embraced automation are reporting improved part consistency and quality, which is why we see this trend expanding in the coming year.

2. Environmental / Sustainability

In an effort to contribute to eco-friendliness and sustainability, the injection molding industry as a whole has been working diligently to decrease energy consumption and create bio-based and recyclable products. Thanks to advances in engineering, newer injection molding equipment now uses between 20%-50% less energy compared to those released just 10 years ago.

Responsible injection molders are also working diligently to reduce the amount of scrap plastics produced in the molding process and gaining efficiencies in doing so. For example, obtaining scrap material that can be repurposed in addition to recycling materials. Taking a few small steps to put sustainable practices into place can (over the course of a few years) save hundreds of thousands of pounds of material from going into landfills.

Many companies are working to strike a balance between their use of conventional plastics and bio-based alternatives. In addition, some organizations are in various stages of development and deployment of plastics, made entirely or in part, from soybeans, corn, flax and other materials, to meet the demand from consumers to save fossil fuels and reduce the negative aspects that traditional plastics have on the environment. Count on more manufacturers to increase their focus on environmental sustainability while reducing their carbon footprint in 2018.

3. Nearshoring

For manufacturers seeking to reduce production expenses, outsourcing of injection molding and/or processes to other countries is an industry trend worth noting. According to one medical device industry expert, the cost difference between injection molding a part in Asia versus North America is actually very small because the labor component is negligible. Electricity is a major component of injection molding, and energy costs are rather universal. So, what’s the element driving the nearshoring trend? Shipping.

The high cost and lengthy shipping times associated with manufacturing components or finished products overseas is forcing many U.S. companies to evaluate their operations and manufacture and ship from locations that are geographically closer. Companies benefiting from nearshoring cite faster delivery, reliability and cost-savings as major factors in their success. Creating long-lasting relationships with injection molders who can act as a partner in your product development process and assist with design for manufacturability also has major benefits. These reasons make us anticipate even more organizations shifting to nearshoring in the near future.

4. Precision Molding

The need for addressing manufacturing challenges swiftly, resolve production issues quickly and help engineers and technicians troubleshoot in real-time is being met by an abundance of technology in our industry – specifically by RJG eDart technology and software platforms like IQMS and Moldflow.

  • RJG eDart:  RJG is a comprehensive and powerful process monitoring tool for injection molding applications. The system helps gain greater control over stabilizing the injection molding processes and ensures parts of the highest quality.
  • Mold Flow: Mold flow analysis simulates how a material will flow through a mold and how the material will orient within the mold. The simulation exposes potential warp and stress points and can help identify areas where sink marks may appear. It can also help to identify where weld lines will be located within the part. Mold flow is an aid in the development of optimal gate location and size. It allows an injection molder to identify stress areas and increase radii in order to eliminate stress points and perfect the tool before the final stages.
  • IQMS: When IQMS application software is used throughout an organization and the molding process, the system can provide a very efficient way to monitor every single step of every single machine in real time to make certain adjustments can be made at a moment’s notice.

5. Metal to Plastic Conversion

While the concept of metal to plastic conversion isn’t new to the industry, the contributions that this process is making in terms of reducing weight, improving fuel efficiency, increasing strength, as well as chemical and heat resistance are striking. Furthermore, factors such as design flexibility and the use of new and improved polymers is causing more and more companies to consider injection molding to meet their needs.

Before moving forward with a plastic to metal part conversion for your organization, we suggest meeting with an experienced design engineer to determine if such a transition is suitable for your product and application.

6. Design for Manufacturability

We’re also noticing an increase in companies working with their plastic injection molders and engineering teams early in the design process. Collaborating with customers at the genesis of their product offers several benefits, including:

  • Selecting the right material for the application
  • Considering radius and wall thickness
  • Ensuring proper gate location
  • Considering draft
  • Including ribs for strength and durability
  • Properly accounting for mold shrinkage

Not only do these elements ensure a smooth manufacturing process of components and/or finished products, it provides the ability for you to go to market quicker while remaining within your budget.

Injection molding plays a vital role in the development of products that serve a plethora of industries. It’s a fluid manufacturing practice that involves a series of complex processes, but finding the right partner makes all the difference in the success of your part. If you’re unsure of how to benefit from the injection molding trends predicted for the year ahead, contact our knowledgeable design engineers, tooling and production experts today.

 

Focus on Lead Times: Using QRM to Get Ahead

Nicolet_PartThis article was originally published by Plastics Business in the winter 2017 issue and written by Lara Copeland, contributing editor.

Business gurus often talk about the view from 30,000 feet – the big picture that provides a look at overall operations. Perhaps, however, the focus should be on the view from 30 feet – a close-up of specific processes and procedures that make an impact now.

Over 30 years ago, at a time when a new home in the US cost an average of $90,000 and many Americans were embracing “Hands Across America,” a small group of four entrepreneurs collaborated and – contributing $300 each – established a plastics manufacturing company in the middle of the Chequamegon-Nicolet National Forest. Nicolet Plastics Inc. (NPI), Mountain, Wisconsin, since has expanded beyond its initial $1,200 investment and one leased press to a 19-press, 42,000-square-foot production facility that focuses on complex industrial and medical components and assemblies. Throughout the years, the company has thrived by pursuing business endeavors and facilitating growth. More recently, Nicolet has set itself apart from the competition by centering its efforts on shrinking lead times and increasing customer satisfaction.

When the global financial crisis struck the country nearly a decade ago, the manufacturing sector did not escape its wrath. Nicolet leaders, aware of the ramifications of surrendering to the recession, realized they needed to act to reinforce the company. Bob Gafvert, business development manager, explained, “Nicolet knew we wouldn’t survive trying to be like the 5,000-plus other molders in the country at that time. We needed to do something different and approach our business in a new way that would further differentiate us from the herd of molders.”

Nicolet reviewed its business and found its complexity score was off the charts when benchmarked against other molders. “In 2010, Nicolet was scoring in the millions while other molders were at a score of 300,000,” Gafvert continued. “We knew our complexity was something we could exploit when the easy, high-volume parts were being sourced off shore.” Wanting to explore options in efficiency, the company contacted the University of Wisconsin-School of Engineering and Dr. Rajan Suri, the founder of the Center for Quick Response Manufacturing.

According to the website for the Center for Quick Response Manufacturing, QRM begins with an understanding that time is the most valuable resource in any enterprise. The QRM methodology was designed specifically for high-variety manufacturers of custom-engineered, low-volume products looking to reduce lead times – much like Nicolet. This companywide approach is geared toward reducing lead times in all phases of manufacturing and office operations and is not to be confused with lean manufacturing – a philosophy focused on eliminating waste for high-volume repetitive production manufacturers.

Rather than eliminating all variabilities in manufacturing processes, QRM focuses on the elimination of dysfunctional variabilities, such as organizational issues that can cause rework, and helps companies find and understand the potential competitive advantages in strategic variabilities. Examples include, “the ability to cope with unexpected changes in demand, a large selection of options for customers and offering custom-engineered products,” according to the website. These strategic variabilities can be huge competitive advantages for companies not interested in higher-volume work, while the elimination of dysfunctional variabilities can cut the longer lead times often associated with highly custom work.

Since Nicolet implemented QRM in 2010, business began to increase. “The marketplace is taking notice of our business model and responding positively to our strategy,” Gafvert said. QRM has allowed Nicolet to compete in the manufacturing arena and gain entry to new prospects. The company has seen significant improvements in quality, reductions in lead time and reduction of inventories. It also has increased profitability and brought products to market more rapidly. Specifically, Nicolet reported reduced lead times for QRM business by two weeks while also reducing setup and changeovers by multiple hours.

“Reducing customers’ time to market and launch of new products has been a continued success. When we help a customer reduce their product launch by weeks and months, we are finding that our commitment to QRM is playing a significant part in delivering and exceeding customer expectations,” Gafvert affirmed. “Whether it’s been on the front end with customer service and orders and acknowledgements or in the quick turnaround of quoting in engineering, we found opportunities for efficiencies in reducing the white space in all aspects of business.”

Presently, Nicolet is continuing its focus on reducing white space – the time a job is waiting between steps, when something is not physically being manufactured in the press – and the company is seeing success with the complexity and diversity of its customer base and their products. As Gafvert acknowledged, “The variability that we experience day in and out is strategic for us, and QRM supports that business model.”

Adopting the QRM approach companywide did come with a few obstacles. “It requires a paradigm shift in terms of manufacturing, such as letting go of certain lean principles, as well as a culture change across the board,” Gafvert added.

To be successful, QRM needs to be employed throughout the company, and it takes time to get everyone on board. As the company has expanded over the last five years, its new hires have had to learn the importance of using QRM and how to support Nicolet’s customers with it. Additionally, getting suppliers on board can pose a challenge. The company is working to educate its suppliers on the value of time and to convince them to adopt a QRM mindset. As Gafvert suggested, “We can’t wait days for a supplier to get back to us with pricing or availability on a material or assembly part because it slows down the process.”

As the company looks for ways to remain prominent in the manufacturing arena, it is “incredible” as Gafvert put it, to see where it all started. Nicolet marked its 30-year anniversary over a two-day period this past fall by offering plant tours and celebrating with its customers (current and prospective), suppliers and the surrounding community. “It was a great opportunity to get people from the area into the facility to see what we do, the level of automation and the opportunities that exist in manufacturing,” Gafvert articulated.

Looking ahead, NPI is expecting continued growth at the facility and through expansion of its customer base. The ability to cope with unexpected changes in demand and its success in providing custom-engineered product in low to moderate volumes has been – and will continue to be – the cornerstone for Nicolet’s progress. “Our plan is to spend another 30 years in our community,” Gafvert asserted as he discussed his enthusiasm for developing the next generation of production, master molders, engineers and customer service staff. He concluded, “Nicolet will continue to focus on driving value to customers who see the opportunity in a relationship with us based on overall value and partnership.”

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