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Struggling to design a plastic injection molded part that meets all necessary specifications and is free of deformations and flaws? The problem is likely stress — or, more accurately, residual stress.
When a plastic resin is melted down prior to injection, the molecular bonds of the material are temporarily broken due to the heat and sheer force of the extruder. This allows the molecules to flow into the mold. The bonds then reform as the material cools, but the stresses on the material remain.
How Residual Stress Affects a Part
Residual stress does not always manifest in the same way. The resin material, melting temperature, and specific injection processes all play a role in how stress occurs, and even the tiniest variable shifts can lead to notably different physical manifestations.
Residual stress can lead several forms of distortion. Warpage, a type of stress caused by relaxation distortion, is especially common. Unfortunately, residual stress warpage is generally undetectable until the part is already in use, when real-world fluctuations in temperature bring the stress to light. Sink marks — part surfaces that have become depressed below their intended plane — are frequently found in warped parts and can present both structural and aesthetic issues.
Cracking and crazing, which produce a series of extremely fine micro cracks, are also common manifestation of residual stress. Parts that are subjected to chemicals, environmental exposure, and temperature extremes may be vulnerable to cracking or crazing.
Residual stress and its related issues can ultimately lead to premature part failure, but this can be easily avoided if armed with the right knowledge.
Residual Stress Solutions
First, select your material carefully. Residual stress in plastic injection molding is unavoidable due to the simple physics of the process, but certain materials are more prone to physically manifesting that stress than others.
You also can prevent residual stress by designing smooth transitions between different features of your part and including rounds, fillets, and other special features in areas likely to experience high stress.
To learn more injection molding basics that can help with your next project, download our free injection molding glossary today.
US Business Executive, a platform for business leaders across the country has featured Decatur Mold in the latest fall issue. The issue focuses on leadership in the areas of general counsel, agriculture, technical education, and manufacturing. Decatur Mold fits well into the manufacturing category as a company that has provided 50 years of leading plastic injection molding and full-service tooling.
Decatur Mold is excited to be amongst the companies highlighted in the issue for long-standing and exemplary business. Our own Vice President, Larry Waltz, states in the article:
“This is our 50th year of business so we have a lot of experience and extensive knowledge in tooling. We’re not tied to one industry. Our expertise spans a range of industries and we serve customers nationwide and throughout North America.”
These industries served across North America choose from full-service molding for a range of designed and tested parts, complete with world-class quality standards. Decatur’s ITAR certification, FFL License 7, and ISO 9001:2008 certification allows for seamless integration into any industry with compliancy requirements or standards. Some of the primary customers served, as mentioned in US Business Executive include automotive, OEMs, tier 1 manufacturers, and large component assemblers.
A Longstanding Injection Molding History
As Decatur Mold’s Vice President Larry Waltz states, “we have no shortage of experience or capabilities, we serve customers in the most efficient and productive manner possible. With a staff of 120 employees in areas of office personnel, tool design, program management, estimating, sales, service, and manufacturing tool makers and processors, we have been able to maintain our core values and service since 1966.”
Injection molding and tooling has always been at the forefront of our company. In the 24/7 on-call shop, Decatur focuses on faster lead times, lower costs, and responsiveness to customers. Working around the clock with access to flatbed delivery drivers are one of the many aspects that sets us apart from other manufacturers.
More Inside US Business Executive
Inside the issue you can learn more about our manufacturing process and look into our facility with its state-of-the-art equipment, trained technicians and expert engineers.
You can also discover:
- The story of Decatur Mold: how we began in 1966
- What makes our company different from other manufacturers
- The capabilities that drive our business
- Decatur Mold’s relationship with our customers
Want more? Learn about one of Decatur Mold’s premier services, prototyping. As a holiday thank you, we’ve compiled a resource so that you can learn the ins and out of prototyping with our Rapid Prototyping eBook. Download the eBook by clicking this link or the button below.
The Federal Firearms License type 7 allows manufacturers to better serve, accommodate, and securely meet customer needs. Working within the military sector for many years, Decatur Mold is proud to announce that we have recently acquired our FFL certificate.
What does the FFL Type 7 mean?
This license, issued by the U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives allows Decatur Mold to manufacture firearms, firearm components, and non-destructive devices for your projects.
The FFL enables manufacturers to produce 100% gun parts, compared to other manufacturers without the FFL, who can only produce 80% of these parts. Those with their FFL can work with you for the entirety of the parts project, showing that fully certified manufacturers are the more efficient and trusted choice.
In addition to this certificate, Decatur Mold is also certified in International Trade in Arms Regulations. The ITAR Registration is a government regulation pertaining to defense exports. This registration is enforced by the Department of State.
Applications in the Military/Defense Industry
In one of Decatur Mold’s past projects for the military industry, the customer had parts that were over the designated weight limit for their defense application. When we worked with this customer, we found that the material type was not the best fit for the part, so we worked to find the ideal fit that would pass tests. Once the correct material was determined for the design, the customer’s parts passed the required tests.
Certifications and industry experience show how a manufacturer is committed to your project and it’s success in your application. When a manufacturer has certifications related to your business, they adhere to the standards you need. At Decatur Mold, our team strives to be recognized and respected as one of the premier mold suppliers, dedicated to world-class quality standards.
To access our FFL Type 7 today, click here or below.
With dozens of factors to consider before beginning an injection molding project, designing a successful part can be challenging.
You understand your part and its application as well as its relation to other parts; you’ve carefully selected a resin; you’ve spent countless hours meticulously designing the part. But are you ready to begin the injection molding process?
Know When You’re Ready to Start
There are a number of indicators that your part is ready to enter production, or that you are at least at the point where you can start contacting injection molders. Consider these criteria a sort of Injection Molding 101, outlining the basic requirements to fulfill before beginning your project.
These are all fairly standard requirements — if you are missing any of them, you may be moving too quickly. Below, we’ve delved into some of the most important factors to keep in mind.
Understand Your Application
This may seem obvious — after all, if you are designing a part, you likely have knowledge of its application. But how deep is that knowledge? Are you familiar with every possible use case? Have you identified every form of stress your part will be subjected to, or calculated how strong this stress may be?
It’s imperative to review the application for your part thoroughly before moving ahead with the production process.
Have a Material in Mind
There are hundreds of plastic resins available for injection molding, not to mention a virtually unlimited number of customized combinations of different resins.
Each resin has different chemical and physical properties. Some are resistant to environmental conditions such as sunlight and temperature fluctuations, while others are weak in that area but perform well in continually high-temperature or caustic environments.
While “strength” is a common go-to attribute, simply selecting the strongest resin will not necessarily result in a part that performs well in its application.
Be Prepared for Production
There also several production-related considerations to take into account before reaching out to an injection molder.
First, know how many parts you need. Second, have a CAD or similar file ready — generally this is not required, but it’s very helpful to the injection molder and can save a considerable amount of time. Third, know the timeframe in which you need the production run completed. Finally, not all injection molding methods are created equal — be sure to do your research and determine which specific injection molding production process will best serve your injection mold design.
These three must-haves are just a sampling of the factors to consider before approaching an injection molder and beginning the production process for your part.
At Decatur Mold, we’ve been providing top-quality injection molding services since 1966. Our 87,000-square-foot facility operates around the clock, 24/7, and we’re proud to offer our customers quick service for all their injection molding needs.
To learn more about how to best prepare for your injection molding project, visit our webpage on Injection Molding here or read up on the basics of rapid prototyping by clicking here or the button below.
To most people, plastic is simply plastic, the material that makes up shopping bags and household products. Those in the commercial and industrial manufacturing fields, however, know that the field of plastics is expansive and diverse.
There are thousands of different plastics, with more constantly being developed. When choosing the right type for your specific application, various considerations should be taken into account — different plastics are derived from different raw materials, synthesized with different methods, feature different physical properties, and are suitable for different uses.
Another variable to consider— one of the most important, in fact — is the tolerances that can be held.
A tolerance is the measurement — usually calculated in fractions of an inch — specifying how much a given feature of a part may deviate from the specified measurement. For example, if an injection molded part is specified to be 1 in. long with a tolerance of 0.1 in., completed parts between 0.9 in. and 1.1 in. long would be acceptable; completed parts that are 0.89 in. or shorter or 1.11 in. or longer would not be acceptable.
Tolerances are set to ensure the proper performance of your part; parts out of tolerance can cause any number of issues in their end application. Tolerances can also vary depending on materials and processing methods.
Because of this, designing a part and selecting its material and production method can be a challenging process.
Balancing Tolerance and Cost
The tighter the specified tolerances of a part, the more expensive that part will be to produce. Why? To put it simply, maintaining tighter tolerances requires more work.
Producing parts to tighter tolerances often requires specialized tools and equipment, which are more expensive to purchase and operate. Both tooling and completed parts must be subjected to more thorough and frequent quality assurance checks, which also add to costs.
Additionally, parts with tighter tolerances are rejected more often for being out of tolerance. This leads to more raw material requirements, higher scrap rates, and lower yields of completed parts, all of which add to production expenses.
Find the Right Tolerance
Finding the correct tolerances for your parts can be a challenge. Understanding the different plastics that are available for manufacturing your part — and, more importantly, the different tolerances that each of those plastics can maintain — will ensure a successful end product.
Decatur Mold has been an industry–leading injection molder since 1966. Over our 50 years of experience, we have developed extensive knowledge of common molding plastics and the tolerances they maintain. We’ve collated this knowledge into a useful, easy–to–read guide, our Molding Tolerances Chart.
Download our Molding Tolerances Chart and learn what tolerance is right for your project’s material , or click the button below for more information.
Rapid prototyping is used to quickly produce a physical sample of a new design to test out form, fit, and function. To keep costs down, prototypes are typically made of less expensive materials than would be used for the final product in case several design test runs are required. The speed of this process helps to decrease time to market.
The rapid prototyping process involves transforming a 3D computer-aided design (CAD), drawing into a physical object by successively layering and solidifying a material.
The Advantages of Rapid Prototyping
Rapid prototyping allows manufacturers to quickly produce a part that they can showcase to potential customers and investors before moving forward with a design. With a physical sample in hand, manufacturers can easily demonstrate the look, size, and functional features of their product, as well as experiment with different colors and textures.
This process also streamlines production; the ability to rapidly produce samples allows manufacturers to quickly test, identify, and correct any design flaws, thereby ensuring that the final product is suitable for its working application. This reduces time and money spent on multiple production runs and hastens the overall time to market, better allowing manufacturers to capture fleeting sales opportunities.
Rapid Prototyping Mold Options
Molds for rapid prototyping can range from limited production, economical options all the way to high-production, higher-cost options; each option is best suited for a particular type of prototyping run:
- Class 105 Mold: Typically made from cast metal or epoxy, Class 105 molds offer sufficient strength for limited-run prototype molds but only last for a maximum of 500 cycles.
- Class 104 Mold: Employed for limited production using non-abrasive materials, moderately priced Class 104 molds are made from mild steel or aluminum, making them optimal for fewer than 100,000 cycles.
- Class 103 Mold: Used for low to medium production of fewer than 500,000 cycles, Class 103 molds are offered at a common price range.
- Class 102 Mold: Well-suited to abrasive materials and parts requiring close tolerances, the medium- to high-production Class 102 molds can be used for cycles of up to 1 million; because of their higher quality, they are fairly high priced.
- Class 101 Mold: Ideal for extremely high production, these high-quality (and therefore highest-priced) molds are used for cycles of 1 million or more.
At Decatur Mold, a turnkey injection molding company, we have the ability to rapidly prototype parts in any volume; we do not require an order minimum. We also produce a myriad of molds for prototypes to high-production complex parts. Since 1966, we’ve been providing top-quality design, prototyping, machining, and tool and die services for a wide range of industries, including automotive, appliance, military, and medical.
To learn more about rapid prototyping and determine which mold option or prototyping method is right for you, we invite you to download our free comprehensive eBook, “The Basics of Rapid Prototyping.”
Through multiple economic recessions including the latest in 2008/9 and the resultant plastic tooling industry consolidations over the years, it is quite a feat now a days to be celebrating fifty years as a privately-held, independent, injection mold tool maker. Yet that is exactly what Decatur Mold Tool & Engineering is doing this year, celebrating its 50 year anniversary. Only a few Tool Makers have been in business supporting the Plastics Industry since 1966. The company has grown from its humble beginnings with only 2,400 square feet in one, low-ceiling building supporting 5 employees to 85,000 square feet and 125 employees in two locations. Interestingly enough, that original building is still in use today on the Decatur Mold facility housing some grinding and wire EDM equipment that is used on a daily basis.
The Decatur Mold of today is a much different and improved image of its former self. Utilizing today’s tool design software and state of the art metal cutting equipment, molds can be produced and serviced much faster and with greater precision than years past. Whether it be prototype or production part requirements, Decatur Mold has the skills and experience to deliver. The industry has changed drastically over fifty years and Decatur Mold has invested in the latest technologies to keep pace.
Decatur Mold chose to celebrate the Anniversary recently with three Customer Appreciation Days from
May 17-19 with daily drawings, door prizes, tours and of course, food. Over the three day period, fifty-four customers representing twenty-three companies made the trek to North Vernon, IN to help celebrate the occasion. Many more customers sent their well wishes, but could not be in attendance given their busy schedules.
Employees at Decatur Mold are very grateful for their customers’ business, recognizing improvements are needed each and every day so Decatur Mold can continue to earn and enjoy many more years of livelihood. Congratulations Decatur Mold on fifty years of mold making and thanks again to all those in attendance.
Following up on a successful campaign of industry trade show appearances, Decatur Mold is very excited to announce that we will once again exhibit at the Amerimold 2016 show which is located this
year in Novi, MI at the Suburban Collection Showplace this coming June 15 and 16 from 9am-3pm.
With several customers already in this region, we look to expand our base at this show.
Michigan is a hotbed for the plastics industry and the automobile industry in particular. We aim to make our presence known to OEM’s and Tiered suppliers that will be in attendance.
When Decatur Mold decided last year that we would look to expand our market base beyond the solid base of customers we have here in the Midwest, it was determined that we would ”dip our toe” into the world of trade shows and attend the Amerimold 2015 show which was located in Rosemont, IL. Admittedly, we had expectations to not only connect with current and past customers but most importantly, we needed to network and meet with new potential customers to make this investment pay off. Last year we had over 200 people stop by our booth. Needless to say, after months of follow up calls,
Admittedly, we had expectations to not only connect with current and past customers but most importantly, we needed to network and meet with new potential customers to make this investment pay off. Last year we had over 200 people stop by our booth. Needless to say, after months of follow up calls, emails and meetings, we have established multiple new customers and sales opportunities to more than make this a worthy investment!
So if you’re in the Novi, MI area this coming June let us know because we have a FREE exhibit hall pass for you! Make plans to attend this show and chat with us at booth 137.
We are celebrating over 50 Years in the industry! Even through changes in technology, since 1966 Decatur Mold’s commitment to the customer, Our Quality, and Our Employees have not changed.