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What is Plastic Injection Molding?

D&M Plastics has been an industry leader in injection molding for nearly 50 years. Driven by a dedication to quality, our team is ISO 9001:2015 certified quality management system and ISO 13485:2016 certified quality management system certified. Our 56,000-square-foot facility houses 30 presses, a cleanroom, and a tool room, leaving us well-prepared to serve as your single-source injection molding provider.

Plastic Injection Molding

Plastic injection molding is a manufacturing process that uses machinery to melt and pressure-inject plastic resins into precisely constructed molds for the mass production of plastic components. Material and design can be adapted to address the requirements of a wide array of applications in industries from aerospace to medical. Plastic injection molding is highly versatile, easily scalable, fast, and cost-effective.

There are three key steps in the plastic injection molding process:

1) Product Design

This initial step requires close collaboration between designers, molders, and product stakeholders to ensure that function, aesthetics, manufacturability, and other considerations are adequately addressed before creating a mold. Attention to detail in this step will prevent unexpected expenses later in the process.

Using CAD software, collaborators will make decisions regarding factors such as:

• Material selection
• Critical tolerances
• Gate styles and locations
• Draft and shutoff angles
• Texturing and finish requirements
• Wall thicknesses

Once the design is complete, a prototype may be made for further analysis.

2) Mold & Tooling Design

After the design is approved, a mold, runners, gates, sprues, and any other necessary tooling must be engineered for use in the injection process. Mold design is crucial to the project’s overall success, as errors in this step could result in the production of aesthetically displeasing, functionally deficient, or otherwise incorrect products. The tooling development stage also provides another opportunity to minimize product defects by fine-tuning or revising details from the initial design stage to improve manufacturability.

Mold material selection is a critical element of mold design. Commonly used core metals include stainless steel (hardened or pre-hardened), aluminum, and a beryllium-copper alloy. Material selection for the mold depends on factors such as:

• Cavity requirements (single or multiple)
• Estimated cycles or runs
• Product material
• Project budget

The primary goal of the mold-making process is to produce a mold that is manufacturable, durable, functional, and low maintenance at the lowest possible cost. Upon completion of the mold design, sample parts are filled and approved, and the tooling process is documented before manufacturing begins.

3) Manufacturing (Creation)

When designs are complete and a mold has been cast, manufacturing or product creation can begin. There are four stages in the manufacturing cycle:

1. Clamping— mold halves are closed and clamped together
2. Injection— molten plastic is pressure-injected into the mold cavities
3. Cooling— plastic cools and hardens to the shape of the mold cavities
4. Ejection— mold opens, and the plastic part is pushed out

Manufacturing of a component lasts only seconds to minutes depending on the size, material and complexity of the part, so the process can be repeated rapidly to create a large quantity of consistent, high-quality components in a short window.

Advantages of Plastic Injection Molding

Plastic injection molding is a highly versatile approach for producing plastic parts, offering numerous advantages over other manufacturing methods. Some of these benefits include:

• Scalability. After the designs and processes are fleshed out, it is inexpensive and straightforward to increase production volume.
• Detailed features and complex geometries. The high pressure used to fill molds forces molten plastic to firmly adhere to the mold’s shape, allowing the material to capture details more adequately.
• High-efficiency production. Once molds are designed and processes programmed, run cycles take mere seconds or minutes to complete, and outputs are more consistent.
• Enhanced product strength. Ribs or gussets can be included in the mold design to account for the flexibility or stiffness required of a component.
• Ability to use multiple plastics simultaneously. Co-injection provides an opportunity for filler plastics to be combined with the base resin to improve product strength, reduce material costs, or provide the physical or mechanical benefits of another plastic.
• Flexibility. From materials to color to design, the plastic injection molding process is easily adaptable for any application.

Plastic Injection Molding by D&M Plastics

Plastic injection molding is versatile, cost-effective, and efficient. The D&M Plastics team can guide you through the entire plastic injection molding process, from product design to manufacturing. We offer an extensive range of plastic materials and have onsite capabilities for end-to-end service, including value-adds like overmolding, insert molding, mold labeling, and more.

For more information on our injection molding capabilities, request a quote or contact us today.

D&M Plastics has been an industry leader in injection molding for nearly 50 years. Driven by a dedication to quality, our team is ISO 9001:2015 certified quality management system and ISO 13485:2016 certified quality management system certified. Our 56,000-square-foot facility houses 30 presses, a cleanroom, and a tool room, leaving us well-prepared to serve as your […]

Avoiding Plastic Injection Molding Defects

D&M Plastics utilizes the latest plastic injection molding technology to create high quality parts for a diverse range of industries. Typically used for mass production, plastic injection molding is a process which allows manufacturers to create immensely high volumes of the same part within tight tolerances. While this process has numerous advantages, errors in the plastic injection molding process or tooling setup may cause defects that impact the appearance or functionality of the final product. Understanding these potential issues makes it easier to avoid them in future projects.

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Avoiding Plastic Injection Molding Defects

Here are some of the most common defects to watch for during the plastic injection molding process:

Burn marks

These discolorations appear on the outer surface of the component and may be black or rust-colored. They are often caused by trapped air or resin overheating within the mold. Shorten the mold cycle time or lower the mold temperature to avoid burn marks. Adding venting can help with trapped gas.

Flow lines

Although they typically do not impact the functionality of a product, flow lines—off-color streaks or patterns across a product’s surface—may look unprofessional when visible to consumers. This defect is caused when plastic cools too rapidly during the injection molding process. Increasing the nozzle diameter and injection speed will help prevent flow lines.

Short shots

Short shots weaken the part and are commonly caused by a lack of molding pressure, which results in trapped air within the product.

Sink marks/voids

When the plastic does not have enough time to cool within the mold, the surface material may shrink inward. This results in surface depressions known as sink marks. Increasing pressure and cooling time can help avoid this defect. Proper part design is necessary to avoid sink marks, i.e. uniform wall stock rather than uneven/thick walls. Uneven cooling speeds may also create voids (internal sink marks) within the part. Limit the risk of this defect by increasing the injection pressure or choosing low-viscosity materials.

Weld lines

Weld lines are caused by multiple molten materials colliding at too low a temperature, resulting in a thin line where the materials did not properly bond. This defect can weaken a component. To help plastic injection molding materials bond properly, increase material temperature and injection speed or eliminate partitions within the mold. Proper gate location can help to avoid weld lines.

Discoloration

Often caused when residual resin is left in a mold from a previous project, discoloration impacts the aesthetics of a part. Occasionally, discoloration may also occur when the coloring agent is unstable. Utilizing a high-quality coloring agent and thoroughly cleaning the production equipment between production runs helps reduce the risk of discoloration.

Delamination

One of the more serious defects is delamination, which presents as a flaking surface layer that separates from the surfaces beneath it. Generally caused when the resin is contaminated or exposed to excess moisture, delamination will negatively impact the strength of the part. It can be avoided by properly storing the resin pellets and increasing the temperature of the mold.

Jetting

Jetting appears as a distinctive snaking spray line on the product’s surface. It typically occurs when the molten material is injected too quickly without contacting the mold’s wall. Jetting ultimately weakens the part but may be avoided by increasing the temperature of the material and lowering the injection pressure. Proper gate location can help to avoid jetting.

Eject marks

When a part is ejected too early or with too much force, it can be left with unattractive markings. Waiting until the part is fully cooled and reducing the force of the ejector rods can reduce the likelihood of eject marks.

About D&M Plastics

At D&M plastics, our experienced team crafts high quality molded products at competitive prices from our ISO 9001:2015 certified quality management system and ISO 13485:2016 certified quality management system certified facility. We can mold parts in both vertical and horizontal molding machines at tolerances as low as ±0.001 inches and offer insert molding, overmolding, and cleanroom molding to meet specialized needs. Visit our injection molding services page to learn more, or request a quote to see how we can help with your next project.

D&M Plastics utilizes the latest plastic injection molding technology to create high quality parts for a diverse range of industries. Typically used for mass production, plastic injection molding is a process which allows manufacturers to create immensely high volumes of the same part within tight tolerances. While this process has numerous advantages, errors in the plastic […]

Most Common Materials for Plastic Injection Molding

At D&M Plastics, we specialize in performing high-volume injection molding using state-of-the-art equipment and technology to create tight-tolerance precision parts down to 0.001 inches. Our capabilities include:

• Clean Room Injection Molding
• Tight Tolerance Molding
• In-Mold Labeling
• Insert Molding

We also offer many value-added and secondary services, full service support, and real-time production analysis.

Common Materials for Plastic Injection Molding

Depending on the end-product’s desired properties, there are a multitude of plastic injection molding material options.

Polycarbonate

This material offers very predictable shrinkage, making it ideal for projects which require particularly tight tolerances. Polycarbonate is naturally transparent, strong, and durable, and is a popular choice for protective gear, eyewear, and window parts; however, it is not safe for food applications.

Nylon (Polyamide)

Nylon’s strength makes it an ideal material for mechanical parts, sports equipment, and medical products. It is highly resistant to wear and chemicals, has a high melting temperature, and is durable against impacts.

Acrylic

Acrylic is transparent, and manufacturers often use it in place of glass as it is scratch resistant and has high tensile strength. This material is tasteless, odorless, and free of BPA, making it ideal for food applications.

Polyoxymethylene (POM)

This acetal resin commonly replaces metal in automotive or mechanical parts, such as gears or ball bearings. It has high levels of strength and rigidity, and is resistant to alcohols, motor oils, and many other solvents. However, POM cannot withstand nitric acid or hydrochloric acid.

Polystyrene (PS)

Polystyrene is budget friendly and available in two types: High Impact Polystyrene (HIPS), which is opaque, and General Purpose Polystyrene (GPPS), which is transparent. Polystyrene is popular for single-use items such as petri dishes and food packaging, but it is not environmentally friendly and does not offer significant strength or heat resistance.

Acrylonitrile Butadiene Styrene (ABS)

ABS is a flexible and affordable engineering grade plastic with high amounts of strength and toughness. It is resistant to scratches, offers good impact resistance, and is lightweight. Common uses include electronic casings, phone adapters, and wall socket plastic guards.

Polypropylene (PP)

Popular for food packaging, PP is highly resistant to moisture and chemicals. This thermoplastic has a high melting point and is durable, with good impact resistance and flexibility. In addition to its use in the food industry, PP can be found in automotive components, athletic apparel, and many household objects.

Polyethylene (PE)

Polyethylene is available in two types: High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE). It is affordable, lightweight, flexible, and moisture-resistant, making it one of the most popular plastic injection molding materials. PE can be found in a wide array of products, including prescription bottles, plastic bags, trash cans, and geomembranes.

Thermoplastic Polyurethane (TPU)

TPU provides high levels of tensile and tear strength, withstands high temperatures, and replicates the elasticity of rubber. Manufacturers commonly utilize this material in cable insulation and power tools.

Thermoplastic Rubber (TPR)

TPR combines plastic and rubber, resulting in a material that can withstand harsh environments and chemicals. It is highly impact resistant and is commonly used in catheters and headphone cables.

D&M Plastics for Your Plastic Injection Molding Needs

For over four decades, D&M Plastics has provided our clients with industry-leading custom injection molding solutions. If you have further questions about the best plastic injection molding material for your needs, our team of experts is here to assist you. Learn more about our services, or request a quote to get started on your next project with us.

At D&M Plastics, we specialize in performing high-volume injection molding using state-of-the-art equipment and technology to create tight-tolerance precision parts down to 0.001 inches. Our capabilities include: Clean Room Injection Molding Tight Tolerance Molding In-Mold Labeling Insert Molding We also offer many value-added and secondary services, full service support, and real-time production analysis. Common Materials […]

Martin Tremonti Joins D&M as New Chief Operating Officer

D&M Plastics, an industry leader in custom injection molding for over 40 years, is pleased to welcome Martin “Marti” Tremonti as Chief Operating Officer. Tremonti brings nearly three decades of experience in manufacturing operations, both nationally and internationally.

Marti is an excellent addition to the D&M team, and has a proven track record of success in building strong teams and efficient processes that impact business growth while utilizing lean initiatives that drive key metrics. It’s a great fit.

Tremonti comes to D&M with a wealth of experience in manufacturing and operations. He is a 26-year veteran in automotive manufacturing operations, with 17 years at Magna International, where he helped to establish an international facility which launched a new program that integrated into an existing production line, while upgrading and improving systems and operations. Tremonti holds a Bachelor of Arts degree from Eastern Michigan University.

“D&M has obviously been doing great things for its automotive, medical, electronics and defense customers, with 40 years of success,” said Tremonti. “I’m looking forward to continuing our operational excellence — building strong teams and efficient processes for continuous improvement.”

For more than 40 years D&M Plastics has provided our customers a comprehensive guarantee of quality, delivery, and price. D&M specializes in tight-tolerance precision parts for the medical and electronics industries, and in 1993 was the first U.S. full-service turnkey manufacturer awarded ISO-certification. In an industry where precision counts, D&M has high ranks, with an external defect rate of 17-PPM’s versus an average industry rate that is 10x higher. The D&M manufacturing team stands behind our customer goals and outcomes, and has more than 275 combined years of injection molding experience. D&M is a privately held company, located in Burlington, Illinois just outside of Chicago.

We’re proud to welcome Marti to the D&M team!

D&M Plastics, an industry leader in custom injection molding for over 40 years, is pleased to welcome Martin “Marti” Tremonti as Chief Operating Officer. Tremonti brings nearly three decades of experience in manufacturing operations, both nationally and internationally. Marti is an excellent addition to the D&M team, and has a proven track record of success […]