Defining Precision in Injection Molding
When we hear the term precision, you might think about a Swiss watch, a fighter jet, a robotic surgery arm. Across the board, precision is defined by accuracy.
What does accuracy mean in molding terms? Precision molding requires all of the factors that control the injection molding process to be at best-in-class levels. This includes the molding equipment, the mold, the resin, the process used to control the molding, and the people working on the project. Each of these important factors all have strict requirements and specifications that must be met to be able to produce molded products that can be called “precision”.
Resin: Where Challenges Arise
Let’s start with resin. In the injection molding process, resin is typically the largest variable and the one item that creates the most challenges. As advancements in resin technology have been made, allowing molded products to achieve new and enhanced functionality, this has created new challenges for the molder. Higher melt temperatures, cooling temperatures, and resins that flash in micro portions of an inch all can accelerate tool and equipment wear.
Resin itself has myriad limitations that affect the achievable level of precision in any given part configuration. Glass-filled materials that can withstand elevated temperatures tend to cause molded parts to warp or distort. All resins have limitations on dimensional accuracy and repeatability. Not every resin can maintain a tolerance of .001”, especially when these dimensions must meet a capability of 1.33 CpK or better.
Included in the resin topic are the requirements for proper handling, storage, drying and conditioning of the resin prior to molding. Normally, precision parts include a requirement for 100% virgin resin. Precision parts may include a requirement for narrow-spec material. All resins have a range of performance. Precision parts require a narrow performance range.
Eliminating Variability
To achieve a manufacturing process that can support molded products at a precision level, process variability must be eliminated as much as possible. You can’t afford unexpected surprises during serial production. The mold and the molding equipment should be standard and not change over time – this is a key way to prevent variability. The mold is made from tool steel, and its shape and size should not change over time, except for minor changes caused by wear, abrasion, or corrosion. The molding press should not change over time either, except for a few high-wear items.
Another important item to success is up-front planning. Injection molding is a process involving many people throughout many functions of the company, all working together to guarantee a positive result. The process starts with an in-depth planning process (APQP). This is a cross-functional process ensuring all functions in the organization have their needed issues addressed in the planning process. Part of this process is an MFA (manufacturing feasibility analysis). In the MFA process, the product drawing and specifications are reviewed in detail by a team of engineers who jointly determine if the product can be produced as specified or if changes/suggestions can be provided to the customer for review. The earlier the molder can get involved in the planning process, the greater the likelihood of a successful product launch.
At Chemtech Plastics, we begin every new project with a full computer simulation of the mold. This information serves as the starting point for the development of the master process. All of our mold standards are based on best-in-class expectations and requirements. Precision molds are typically an SPI/SPE 101 or 102 class mold. If ultra-tight tolerances are required, tool steel selection becomes very important.
The other main area of focus is the molding press and auxiliary equipment. The press and equipment should allow for a stable, repeatable, and accurate molding process. Variations caused by delays in press functions or wide tolerance ranges in the press’ operation cannot be tolerated. At Chemtech, we purchase electric and hybrid presses, some with planetary drives. Our Sodick press allows for very accurate shot control. These highly sophisticated molding cells require regular routine maintenance to stay at top performance levels.
Another big part of the equipment portion is the highly sophisticated process controller and hot runner controls. Injection molding today is no longer an art form – it is a science. The equipment technology has advanced to a level that allows a precision molder very accurate control of the molding process at a finite level.
Cooling is of great importance for temperature control of the mold and molding equipment. Having a water supply system capable of supplying turbulent flow at every press is a must. Ensuring adequate water flow in every cooling channel should be part of the master process development. The water supply should have the proper flow capabilities, and it must be clean and protected against plaque and buildup in the cooling channels. If not, maintaining proper mold cooling becomes more difficult.
How to Develop a Master Process
The development of the master process should be a statistical study conducted over time. A reliable master process starts with items like a short-shot study, gate freeze analysis, viscosity curve study, and results presented in an optimized master process with the largest possible processing window. When a molded product has a very narrow processing window, it is only a matter of time before a discrepant product is produced. The master process should become a “stake in the ground,” and if the process needs to be changed, the process should stop until the cause of the needed change is found and corrected. To produce precision parts, the process must be stable and repeatable. The main variable is either changes in the resin or changes in the equipment.
Precision Molding at Chemtech
At Chemtech Plastics, we believe the secret weapon to high precision is our people. We tell everybody who visits us, “Anyone can buy capital and equipment, brick and mortar, but you can’t buy a passionate, dedicated workforce.” Successful precision molding demands a passion for excellence. Our process starts with a group of tooling engineers who design and build precision molds for the highly trained process engineers to develop the master process, and then pass the parts off to the quantity engineers who inspect the parts and provide the final quality submission. There is a large support group required to support these technical experts.
Precision injection molding requires all elements of the process to be at best-in-class levels. Chemtech Plastics takes pride in our ability to meet these stringent requirements. We have been supplying precision injection molded components for over four decades. We’ve earned a reputation for supplying some of the industry’s most challenging applications. Whether it’s robotic surgery, safety-critical functions in your car, or your next most important component, Chemtech Plastics is your precision injection molding leader.
- Published in Automotive, Medical
See Why Chemtech Plastics is #1 in Multi-Shot Molding
What is Multi-Shot Injection Molding?
Multi-shot injection molding is a form of precision molding that molds two or more materials onto each other in one plastic molding cycle. The end result is an integrated part with multiple distinct aspects. Multi-shot injection molding is used in numerous industries, such as automotive, consumer products and medical – just to name a few.
The two most common types of multi-shot injection molding are:
- Two-shot (2K) injection molding molds two different materials, colors or components together in a single cycle
- Three-shot (3K) injection molding molds three different materials, colors or components together in a single cycle
Whether to use 2K or 3K multi-shot injection molding is highly dependent on the needs of each individual project. While 2K is more commonly used, 3K is utilized for more intricate items. Chemtech Plastics utilizes exclusively 2k molding for medical components, but we specialize in both 2k and 3k in multi-shot molding for other industries. We can help guide you in the right direction for your unique project.
Multi-shot injection molding has a number of benefits. From a design perspective, this process accommodates greater flexibility to execute complex designs and features. This is useful for a part that is made of different materials or textures, like a part with a grip that incorporates both a hard and soft texture. Multi-shot molding also provides enhanced aesthetic benefits, since it can create one product with multiple colors.
Multi-Shot Injection Molding in the Medical Industry
The medical industry requires the manufacture of millions of parts per year. Due to our strong background in medical manufacturing, Chemtech Plastics engineers high-volume automated assembly lines that can not only meet production demands, but surpass them.
Chemtech Plastics has formed strong partnerships with medical device manufacturers that specialize in surgical and diagnostic applications. Our leading-edge multi-shot medical injection molding capabilities, high standards for design and manufacturing, careful selection of medical-grade materials, and our rigorous quality control measures set Chemtech Plastics apart.
Design for Manufacturing in Medical Multi-Shot Injection Molding
Design for Manufacturing (DFM) is an essential first step in designing complex medical parts. DFM is a process that determines the simplest and most cost-effective way to manufacture a part. Key considerations for DFM in multi-shot injection molding for medical parts are:
- Material. Medical parts must be biocompatible (being compatible with a living being without causing an adverse effect) and able to withstand sterilization and chemicals. Chemtech Plastics has extensive knowledge of the application and use of medical-grade and FDA-approved materials, including polycarbonate/acrylonitrile butadiene styrene, polyether ether ketone, and more.
- Dimensional accuracy. Tolerances for medical parts are incredibly tight. Designing multi-shot molds that can accommodate such precision is critical to manufacture a part that lives up to industry standards. Chemtech Plastics’ highly experienced team and specialized technology consistently design precise molds that are free from errors like warping and shrinkage. We produce tight-tolerance molded plastics with Class A surface finishes.
- Complex geometries. The designs of many medical parts are very complex. Chemtech Plastics can utilize our 2k multi-shot molding capabilities to design molds for parts with intricate and diverse features.
At Chemtech Plastics, all project stakeholders are involved in the DFM process, from designers and engineers to mold builders and technicians, working cross-functionally to challenge the design and come up with the best possible final product.
Meeting Industry Demands for Quality Control
In an industry that is quite literally life or death, strict quality control for every part of every device. Chemtech Plastics employs a DQS-Certificated quality management program that emphasizes defect prevention, reduction of variation and waste, and continuous improvement.
Chemtech Plastics also utilizes cutting-edge automation technology throughout the manufacturing process to ensure the parts we produce live up to our high standard of quality. For example, our automated assembly lines increase part consistency and reduce errors. We also employ an automated data collection method that provides process validation and component or device traceability, along with machinery validation.
If you have a medical part project that requires multi-shot plastic injection molding, partner with the industry leader. Chemtech Plastics manufactures critical medical component parts for diverse applications including robotic surgery, instruments, and tools, as well as medical operating devices for some of the world’s leading medical companies. For over four decades, Chemtech Plastics has been an industry-leading, full-service precision injection molding company, with both DQS-Certified for IATF 16949 : 2016 and ISO 9001 : 2015. Our state-of-the-art facility and dedicated team allow us to successfully take on tight-tolerance, critical-to-function projects. Contact us today to start your project.
- Published in Medical
Precision in Medical Plastic Injection Molding
To protect and support the lives of patients and the roles of medical staff worldwide, medical and surgical components must be of the highest quality. One of Chemtech Plastics’ top specialties is crafting medical device components with our leading-edge medical plastic injection molder capabilities. With an emphasis on experience, quality control, and transparency, we are the medical plastic injection molding to turn to when you need precision components.
Our Technology
Amid our 135,000-square-foot facilities, Chemtech has 54 plastic injection molding machines of varying capacities and capabilities. These include the TOYO Si-6 Series, ARBURG Allrounder 520 S, and Sodick GL 150, to name but a few. Narrowing in on Sodick’s technology, these machines are highly accurate, reliable, and stable—perfect for producing and reproducing tight-tolerance components for medical equipment.
Our Range
We are well versed in a variety of premium plastic injection molding materials. PEI, or polyetherimide (Ultem®), is an excellent example of a stiff, durable plastic most often utilized for medical or scientific purposes, such as medical instrument parts. Chemtech understands the importance of using high-performance engineering-grade resins to obtain quality results. This goes hand-in-hand with having a team with expert-level skills to correctly process these unique, high-temperature plastics and specific custom molding machines.
Our Team
Precision is not only tight tolerances. Precision is also knowledge, communication, and relationships. We maintain partnerships with several medical device manufacturers specializing in surgical and diagnostic applications, thanks to our experience in medical manufacturing.
Do you have a project in mind? Request a quote from Chemtech Plastics today.
- Published in Medical
