In our previous blog, we talked about the most common types of thermoplastics used in injection molding and how they compare against each other. Today, we’ll be going over improving the characteristics of resins with plastic additives.
What are plastic additives?
Plastic additives are compounds added during the formulation of the resin to improve the mechanical properties of plastic. Whether you are looking to impart heat resistance, improve structural integrity, increase lubricity, or enhance other characteristics, plastic additives can be a great way to heighten current attributes or add new properties to preexisting plastic. At GMN, we have access to a large variety of plastics additives to solve almost any production challenge.
What are the different types of plastic additives?
Glass and carbon
Carbon and glass are commonly used material additives that add structural integrity, toughness, and rigidity to a thermoplastic. They are helpful when a part needs to support weight or endure a harsh environment for extensive periods. While the amount of glass or carbon added to a resin can be highly specified, given how abrasive this additive is, adding too much can prematurely wear down tooling.
As the name suggests, fire retardants are compounds added to plastic resins that help inhibit burning. They are particularly useful for materials such as polycarbonate, which may struggle with flammability restrictions. There are different kinds of fire-retardant additives, and many plastics are available with varying amounts of added fire retardant depending on project requirements.
Plastic components are often subject to damage when exposed to direct sunlight or other ultraviolet light sources. Extended exposure can diminish the mechanical performance and alter the color of a plastic part. Adding UV stabilizers to the plastic can protect components from degradation and discoloration resulting from subjection to ultraviolet rays.
Colorants are plastic additives that alter the color of plastic. Unlike other additives which are added to plastic during formulation, colorants can be mixed in during injection molding to help achieve custom colors. Whether a part needs to match a specific color for branding purposes or simply needs to add contrast to a design, colorants allow most thermoplastics to achieve nearly infinite color possibilities.
Depending on how a component is designed, it can sometimes be difficult to remove it from the tool. Often, this issue doesn’t arise until later stages in the manufacturing process. Instead of completely redesigning the mold, it’s often simpler to use plastic that contains release agent additives. These additives add lubricity to the component, so it can be easily ejected from the tooling.
Teflon is an additive commonly used for high wear and tear applications or parts that face a lot of friction throughout their lifespan. It can help increase the lubricity of plastic, thereby reducing friction when it makes contact with other components and ultimately improving durability.
While the above are the most common additives at GMN, it’s far from an exhaustive list. Additives are frequently mixed and matched with different plastics to create custom solutions for tough injection molding challenges. To discuss your specific plastic component needs, schedule a consultation with our experts.
When it comes to designing a new plastic component, it’s important to realize that no material is a one-size-fits-all solution. Characteristics such as cost, temperature resistance, manufacturability, impact resistance, and structural integrity can vary widely between resins used for injection molding.
Considering all the different polymers and blends available, how do you decide which one is right for your next project? Below, we’ll be highlighting the key features of the most commonly used thermoplastics here at GMN.
What are the most common types of plastic for injection molding?
Commodity plastics are inexpensive plastics typically used for high-volume applications. The two most popular commodity plastics at GMN are polyethylene (PE) and polypropylene (PP). Both are very versatile resins that are buoyant, hydrophobic, and chemically resistant, making them ideal for a variety of plastic products.
While PE and PP both have decent impact resistance, they aren’t as durable as other plastic materials and are susceptible to damage from ultra-violet light exposure. The two resins are favored for cost-effective and lightweight items, such as reusable water bottles, toys, and disposable plastic packaging.
Acrylonitrile butadiene styrene:
Acrylonitrile butadiene styrene (ABS) is one of the most commonly used materials at GMN Plastics. A naturally high-sheen resin, ABS has high levels of impact resistance and strength, making it an excellent choice for bezels and housing.
ABS is also available with several additives (such as glass, colorants, or Teflon) to enhance its inherent mechanical properties. It also tends to be relatively inexpensive, making it ideal for high-volume applications that may require more durability than a commodity plastic.
Polycarbonate (PC) is ideal for a multitude of projects due to its versatility. Polycarbonate has good electrical insulation, impact resistance, heat resistance, and fire-retardance. Polycarbonate is also naturally transparent, which means it’s a good choice when clarity is important as it can easily be matched to different colors with the addition of colorants.
While it isn’t quite as inexpensive as commodity plastics like PE and PP, polycarbonate tends to be reasonably priced. Many different grades of polycarbonate are available with varying levels of additives for additional strength, making it ideal for a wide variety of projects.
Engineering polymers are a family of highly engineered resins that have exceptional mechanical properties. While the exact characteristics differ, they generally have high impact resistance, stiffness, chemical resistivity, flame retardance, and heat resistance.
Often used in highly regulated industries such as the aerospace and medical fields, the most common engineering polymers used at GMN are Ultem (polyetherimide - PEI) and Radel (polyphenylsulfone - PPSU). Polyetheretherketone (PEEK) and other materials as specified. While each of these offers a host of different benefits for plastic injection molding, given how highly specialized they are, they can be expensive and difficult to obtain.
GMN Plastics has decades of experience in not only creating custom plastic components for a wide array of projects but also incorporating them into complete assemblies to provide a holistic solution. To learn more about our injection molding capabilities, visit our website or schedule a consultation with our experts.
Whether it’s etching, engraving, or cutting materials, laser technology plays an integral role in the fabrication and decoration of various components. But how do lasers exactly work? Which materials can a laser cut? What are the key advantages of utilizing lasers in the manufacturing industry? By demonstrating the working of a few laser cutters at GM Nameplate (GMN), our video will answer all the above questions.
How does laser technology work?
As seen in the video, a laser is mounted on an X-Y motion stage of the cutting machine. Installed perpendicular to the substrate, the laser moves across the surface to heat, melt, and vaporize the material. As opposed to a standard flashlight, the light released here is coherent, monochromatic, and directional. The core cutting characteristics, such as depth, speed, and power, are dictated by the wavelength and the frequency of the laser light.
Laser cutting machines at GMN
The laser cutters at GMN can be categorized into the following three types -
- Fiber laser – Creating light by banks of diodes, fiber laser channels and amplifies light through a fiber optic cable. The wavelength created by a fiber laser is ideal for marking and etching intricate patterns.
- CO2 laser – Utilizing CO2 as the amplifying medium, CO2 laser uses an electrical charge to excite the gas in a discharge tube to emit light. The frequency of this laser is ideal for cutting a broad range of substrates.
- Nitrogen laser – Similar to a CO2 laser, it uses nitrogen as the lasing medium to produce the cutting beam. At GMN, a nitrogen laser is employed for cutting aluminum and stainless steel.
To control the quality of the output, the laser cutters can also be accompanied by an assist gas such as nitrogen or air. The assist gas curtains the laser beam to swiftly vaporize the material after cutting, ensuring smooth and unblemished edges. Nitrogen gas assist is particularly suited for projects where upholding the aesthetics of the material is critical. By creating an inert field around the laser, nitrogen gas protects the substrate from unwanted flaming or burning. For any given application, it is the interplay of several factors such as design specifications, anticipated volumes, tolerance requirements, and cost restrictions, that determines the most appropriate laser type to utilize.
With machines ranging from 30W to 400W, GMN employs low-powered fiber lasers for etching and engraving. High-powered CO2 and nitrogen lasers are typically reserved for cutting thicker materials and metals. The wide array of laser machines allows GMN to cut numerous substrates including 3000 and 5000 series aluminum, magnetic (430) and non-magnetic (304 stainless steel) alloys, Lexan, acrylic, foam, polyester, polycarbonate, and vinyl. During laser cutting, calibrating the focus point of the laser beam is extremely crucial to achieve the utmost precision. Most machines at GMN are equipped with a computerized calibration system, where a focal arm travels closer to the material, gauges its thickness, and automatically adjusts the focal length of the laser.
Advantages of laser cutting
Versatile and easy to use, laser technology is extensively utilized at GMN for fabricating materials with extreme accuracy. When compared to other die-cutting techniques, the lead time for laser cutting is extremely short and last-minute changes to artwork can be quickly accomplished. Ideal for rapid prototyping and low-volume programs, laser technology is well suited for cutting complex shapes, creating registration holes, engraving intricate patterns, and etching serial numbers.
To see some of the laser cutters at GMN in action, watch our video below.
We are happy to share that GMN has been honored by Laird Performance Materials as a Preferred Converter for Performance Excellence. Only a select group of organizations throughout North America rise to the level of Preferred Partner.
Laird Performance Materials is a market leader for advanced protection solutions for electronic components and systems. The Preferred Converter status gives GMN direct access to Laird’s performance-critical solutions including, thermal interface materials, EMI suppression, and absorption materials. It also allows GMN to offer custom engineered solutions to our customers at competitive prices and faster time-to-market.
To learn more about this strategic partnership with Laird Performance Materials, read our press release here.
Pad printing is an offset printing process where ink is transferred from a cliché to the required component via a pad. Bringing together a blend of consistency, repeatability, and durability, pad printing can help you achieve intricate patterns and designs. While most decorative techniques such as screen and lithographic printing require a flat surface, pad printing is one of the very few processes that is well suited for decorating gently curved, irregular, textured, and/or cylindrical surfaces. Predominantly seen in the automotive, electronics, appliance, personal care, and medical industries, pad printing is often chosen for applications that will endure significant handling and need to withstand the test of time.
Custom pad printing process
Our latest video was created to not only equip you with the essentials of pad printing, but also to walk you through the step-by-step pad printing process.
- The artwork is etched onto the cliché (flat plate), and ink is deposited into the etched recess.
- A silicone pad picks up the inked image and descends onto the part to transfer a clean, crisp, and lasting image.
- The pad is pressed on a polyester film to remove any excess ink. Comprising of a low-tack pressure-sensitive adhesive, the polyester film removes any residual ink from the pad prior to the next printing cycle.
From standard to programmable multi-axis printers, the video below offers a glimpse into the different pad printing presses utilized at GM Nameplate (GMN). Armed with a rotating fixture, the programmable multi-axis printer is capable of numerous hits in multiple color combinations on different axes, all in a single set-up. This capability eliminates the need to transfer the part manually from one station to the other, resulting in significant time and cost savings.
Pad printing on different substrates
Pad printing is compatible with a broad range of substrates including stainless steel, polycarbonate, polyethylene terephthalate (PET), glass, polyvinyl chloride (PVC), acrylic, and acrylonitrile butadiene styrene (ABS). Very few plastic materials such as low (LDPE) and high-density polyethylene (HDPE), and polypropylene aren’t cohesive with pad printing inks and require a pre-treatment to ensure good adhesion.
Pad printing considerations
For every project, custom fixtures are designed and built to register the component to the pad printing head. The alignment of the ink pad with respect to the size and geometry of the part is specifically engineered to ensure exact registration. As seen with the Nissan badge in the video, the pliability of the silicone pad allows for printing with extreme precision, preventing the ink from coming in contact on the inside walls of the recessed letters. Maintaining the viscosity of the ink is extremely crucial to ensure the ink deposition accuracy and consistency. While the ink needs to be fluid enough to deposit on the substrate, it should not bleed out of the impression area. Thinners and adhesion promoters can be added to inks to achieve the desired viscosity level. Most of the inks used for pad printing at GMN are air-dried and are usually cured in conveyor ovens. Several other factors including the shape, material and durometer of the pad, location and color of the etched artwork, and tilt of the ink pad, are critical to the success of any project.
To see the pad printing process in action, watch our video here.
When a California-based medical company was assembling its new infusion pump, they knew it was critical for every part to work perfectly and be free of defects. One of the most important parts was a custom rear housing that encases all of the internal components of the device. Having worked extensively with GMN in the past, they knew they could trust our team with the production of this vital component.
The housing was complex, featuring an injection-molded plastic casing, 15 separate brass inserts, electromagnetic shielding, and a latch closure. While each component was inspected at various stages of the production process, given the complexity and the assortment of components involved, it was still possible for an issue to be overlooked. While it was rare, this occasionally resulted in a defective part making it through to the next phase of production, where it would be flagged and removed from the production line. Upon further analysis, it was discovered that these occasional defects stemmed from the improper positioning of the brass inserts. Even a single missing or misaligned insert could cause issues during assembly.
To resolve this issue, the experts at GMN decided to implement a custom vision inspection system. This vision system would automate part of the inspection process, lowering the total possibility for error as well as making the production process more efficient. After some experimentation, the team ultimately decided to integrate the inspection system directly into the heat stake where the brass inserts were positioned and inserted.
The vision system consisted of two cameras located directly above the platform where heat staking took place. This allowed the system to verify the presence and proper alignment of all the brass inserts before being injected into the assembly. As a secondary measure, the vision system checked the alignment of the inserts after they were heat staked into the housing.
After adopting the vision system, the defect rate dropped to nearly zero. It significantly reduced the production time, allowing more defect-free parts to be fabricated in the same time frame. The vision system has earned a permanent place at GMN’s Beaverton, OR plant to uphold the quality of the infusion pump housing.
This is just another example of GMN leveraging custom technologies to enhance the quality of its products and improve manufacturing processes. To find out how GMN can help with your next product, request a consultation with our experts.
FLIR, a global leader in thermal imaging camera systems, had developed a line of fixed-mount thermal marine cameras with a protective metal housing. However, their existing housing was not only heavy but also expensive and time-consuming to manufacture. Looking to re-design the metallic housing, FLIR approached GM Nameplate (GMN) for an alternative solution.
As the housing remains an integral part of the thermal camera system, it would be repeatedly exposed to challenging surroundings including ultraviolet rays, seawater, and high winds. Keeping the severe outdoor conditions in mind, GMN proposed to replace the metal housing with a robust, industrial-grade plastic that can endure prolonged marine use and environmental damage. Additionally, plastic is not only cost-effective but also seven times lighter than metal and faster to fabricate. The housing was fabricated via injection molding at GMN’s Beaverton, OR division.
FLIR’s original design also comprised of a chrome-plated logo attached to the metal housing with hooks. The hooks were attached to the metal via heat staking, a process of melting metal to create a bond. However, the seal formed via heat staking was not airtight, causing unwanted water to seep through the crevices and gradually oxidizing the metal hooks and housing. To resolve this sealing issue, GMN switched the original chrome-plated logo with a 3D electroform logo. This unique metal decoration technique deposited nickel and chrome directly on the desired form to create a high-quality, corrosion-resistant, three-dimensional logo. The distinct logo was brought to life at GMN’s Monroe, NC division and adhered to the plastic housing with a pressure-sensitive adhesive. Offering extremely high durability and visual appeal, the finished product flawlessly married plastic with metal.
GMN brought together two of its core capabilities and manufacturing locations (metal decoration at Monroe, NC and plastic injection molding at Beaverton, OR) to effectively meet the needs of the program. Following the successful completion of this project, FLIR returned to GMN to develop both a smaller and larger housing for a similar camera line.
To learn more about plastic decorating capabilities and value-added assemblies, visit our website here.
While plastic injection molding remains the cornerstone of GMN Plastics, plastic machining is one of the many complementary capabilities offered to our customers. With a dedicated area and automated equipment for machining, GMN Plastics can machine parts up to 20”x40” in size. But how does plastic machining benefit our customers? Plastic machining is ideal for secondary machining of injection molded parts. For parts that need to be modified to create a unique part number or multiple from a host molded part, machining is a cost-effective solution to minimize the cost of the tool.
Some of the core advantages of plastic machining include –
- Lowered cost – Depending on the order quantity, utilizing machining over a tool can result in significant cost savings. For instance, machining can eliminate the need for tooling in lower volume projects, thereby reducing non-recurring engineering (NRE) costs.
- Quality control – Machining provides with greater control over part quality and production process. By eliminating the need to sub-contract machining and performing it in in-house, machining has allowed GMN Plastics to reduce paperwork and handling charges.
- Fine trimming and de-gating – Most plastic parts, especially from highly regulated industries such as medical and aerospace, require a smooth finish. Machining can be used to remove the gate from an injection molded part, making the surface smooth and gate-free.
- Taping holes – Machining offers the ability for holes to be taped rather than using an unscrewing tool. While it’s not only cost-effective for lower volumes, it also allows for better control of threads and holes.
There are several factors to consider while deciding between tool and machining. While machining may eliminate the tooling cost, it increases the price per part. So, depending on the volume, tooling may be more affordable. But if you need to change an existing part, secondary machining may be the process of choice.
Currently, GMN Plastics serves customers in nearly every industry with its machining capabilities. To determine if this is a good fit for your next project, request a consultation with our plastic experts.
This blog is the third in our series on statistical process control (SPC). In the previous blogs, we discussed the basics of statistical techniques and process capability indexes. In this blog, we will be focusing on control charts and their core benefits in the manufacturing landscape.
The control chart is a very helpful tool in identifying unwanted variation in a production process. The goal of statistical control is to identify process variation and to determine which variation is beyond our control. While some variations are inherent to the process, others are special or assignable. These deviations are outside of the “normal” variation that we typically see in a process. It can be identified using statistical tools to be reduced or eliminated from the normal process.
To understand control charts, let’s first discuss variation. In a perfect world, there would be no variation. Whenever we turn on a machine, it would produce the exact same part every time. However, we don’t live in a perfect world - machines fail, internal parts abrade, molding tools wear out, temperatures change, and materials subtly change from one production badge to the other. There are several inputs to a given production process that must work together to produce parts that meet customer requirements. By measuring key characteristics of the finished part, we can evaluate the manufacturing process. Using control charts, we can identify inherent variations from special variations (e.g. an injection mold wearing off or an improper machine setting). By eliminating these unique discrepancies, we can return the process to “normal”.
The two types of control charts that are regularly used at GMN Plastics are individual charts and x-bar R charts. As seen in the below example, both these charts feature two elements – 1) a center line which is the mean (average) for the particular data set being studied, and 2) upper and lower control limits which are statistically calculated from the same data set. Measurement data for key characteristics are collected and entered at regular intervals over time.
The control limits, calculated statistically, represent plus/minus three standard deviations from the average (mean). These lines represent the threshold at which the process output is considered to be statistically “unlikely”. In other words, the control limits represent the division of the natural variation of a process from the “unlikely” variation, occurring due to special or assignable causes, that can be eliminated from the process. Data points that appear outside of these control limits or unusual data runs (data increasing or decreasing over six or more successive measurements) should be investigated to determine and eliminate the source of the assignable variation.
One of the biggest advantages of identifying and addressing variations early in the production cycle is to prevent problems before any out-of-specification parts are produced. It maximizes machine and material efficiency, which in turn lowers production cost and time. The various statistical tools employed by the process engineers at GMN Plastics continue to play a pivotal role in meeting customer demands and consistently building high-quality parts.
This blog is the second in our series on statistical process control (SPC). In the previous blog (read here), we learned about the fundamentals of statistical tools and techniques. In this blog, we will be focusing on one of the most commonly employed statistical tools in the manufacturing industry – process capability indexes (Cpk).
Process capability index is an indicator of how the production process is performing with regards to key process control parameters and customer specifications. Besides the obvious reason of satisfying customer requirements, there is another reason to develop and use capability indexes. They can be critical predictors of future performance and a robust method of measuring the ability of production processes to produce high-quality parts consistently.
The letter “C” in SPC stands for control. But, what are we controlling? Statistical analysis of a production process is all about controlling and reducing variation in the process. It aims at identifying and separating the natural causes of variation, that are inherent to the process, from the special or assignable causes that can be controlled, adjusted, and/or eliminated. Process capability is the ability of a process to produce a product that is both accurate and precise. The accuracy and precision of a set of measurements can be illustrated as follows:
Cpk takes into account both the accuracy and the precision of the measurement around the average. Statistical software takes measurement data and shows the process capability as a single number that represents the process’ ability to provide both – an accurate and precise product. At GMN Plastics, we aim for a Cpk of 1.33 or greater for most of our customers. The core benefits of creating a process that delivers high-level capability include optimizing manufacturing time and materials, reducing scraps and re-work, and equipping the production system to create more products in the least amount of time possible.
Ultimately, process capability is all about creating products that meet customer specifications with a minimum variation over time. Stay tuned to learn more about control charts in our next blog. Until then, check out our other blog on Qualification process: Four parts to ensure part consistency.