10 Tips for Polypropylene PP Injection MOLDING

Polypropylene continues to gain popularity in the injection mold industry. With a low-density consistency and chemical resistant design, it is often used to produce items such as medical devices and automotive parts. While polypropylene resins offer a number of benefits, it is important to monitor the temperature threshold during the smelting and printing process. Here are the top 10 tips for injection molding polypropylene resins.

Injection Mold
Injection Mold

1) Make sure you have the right molding equipment

The road to successful injection moulding starts with the right molding equipment. Fortunately, polypropylene can be printed accurately using unchanged one-stage thread molding equipment.

2) Consider pre-drying ONLY if you use certain polypropylene resins

“In most plastic processing factories, resin dryers are standard equipment. An important exception to this is facilities that exclusively process polyolefins such as polyethylene and polypropylene. These are some polymer families which do not require drying because this material family is not hygroscopic. “

Unlike most commercial polymers that are highly polar, polypropylene is a non-polar substance, allowing you to pass the pre-drying process. The only resin that may require pre-drying is some filled polypropylene resin. This advantage allows you to save time during the injection moulding process.

3) Use a melting temperature range of 400 ° F to 500 ° F

Using melting temperatures higher than 500 ° F can cause flashing, warpage, shrinking and burning. Temperatures lower than 400 ° F, on the other hand, can produce poor quality flow and surface markings. When you set your melting temperature, try to reach a melting temperature that is 25-50 ° F higher than the minimum filling temperature.

4) Strives for an injection pressure range of 800 to 1,500 psi

Injection pressure is another variable that can help control common injection moulding problems with polypropylene molding. While the injection pressure you set must reflect the construction and size of the item. In general, the pressure should be able to fill about 99% of the parts to prevent problems with flashing and stickiness.

5) Don’t rush the injection process

Be prepared for the injection process to consume the majority of each whole cycle. While injection time does not significantly affect the warpage, patience with the injection process is important because the accurate injection is a major factor in controlling shrinkage.

6) Choose a mold temperature around 50-150 ° F

The mold temperature must be carefully regulated to reduce stress and surface imperfections. A mold temperature of 50-150 ° F helps prevent this trap. In addition, ensure that the mold is uniformly cooled to facilitate the removal of components from the mold.

7) Never rush time

Hold time plays an important role in preventing warpage and shrinkage. Therefore resist the urge to remove parts of the mold before it is cool enough. Allowing the part to cool to around 130 ° F is recommended to produce satisfactory results.

8) Use minimal back pressure to increase your cycle time

The ideal backpressure for polypropylene injection mold is usually between 50 and 100 psi. Backpressure in this range can help increase your cycle time. Exceptions to this rule of thumb are cases that require mixing pigments.

9) Adjust your mold or polypropylene level if sticking occurs

Sticking is not common with polypropylene because it has exceptional release properties. However, if minor adhesions occur, you can easily improve the attachment by making minor changes to the mold or using a grade of polypropylene that has been lubricated internally.

10) Seek support from trained industry professionals

The only best way to ensure your satisfaction with polypropylene resin injection molds is to seek guidance from a leader in the injection mold industry. We invite you to contact us for further injection mold tips. With almost years of industry experience, we have the resources and expertise to help you develop the unlimited injection moulding process. We look forward to hearing from you!

midplane models

1. Our midplane models are very accurate with best mesh quality. Usually the quality of our midplanes is much better than most fusion models made automatically by Moldflow. 

2. The size of midplane is far less than of fusion models with the same level of details. But in most cases midplane is more detailed model.

3. It is possible to have 3 rows or more of elements on most ribs (it is the minimal requirements for warpage analysis) but keep the very reasonable size of the model. Usually we can see only two or even one rows of elements on ribs in case of automatically created fusion models. It is not good for the flow analysis and definitely bad for warpage analysis.

4. Using midplane model it is more easy to check different thicknesses of ribs in case of problem with filling or warpage.

5. Using midplane model it possible to fully control the thicknesses distribution also in cases difficult for fusion analysis. For example we can accurate represent places on the model at spasmodic change of thickness on a small interval. Such places very important for good analysis but very difficult for fusion models. Usually fusion models gives you very rough results in such cases.

6. For thin-walled parts midplane model are better because fusion model is too rough in thickness’s calculation.

7. The calculation of midplane models is faster. This is important for complex models and in cases of multiple calculations with the aim to find a best solution.

Plastic Moling Company

GC Tech Plastic Molding Company has developed a wide variety of auxiliary equipment to enhance the part quality or meet the customer’s requirement. 1st Tech offers a complete line of secondary operations including:

  • Heat Transfer Decals
  • Hot/Foil Stamping
  • Color Appearance Matching
  • Assembly
  • Specialized Packaging
  • Bar Coding
  • JIT/Kanban Delivery Systems

GC Tech Plastic Molding Company was founded in November of 2005 in DongGuan China to provide fully integrated thermoplastic injection molding services including industrial and mechanical design, prototyping, mold fabrication, high capacity molding, plastic mold, part decorating, secondary operations, the assembly including electronic and mechanical subassemblies and fulfillment.   GC Plastic Molding Company is a customer-driven organization that enables customers to bring high-quality products to market faster and at reduces costs by combining a multi-disciplinary team of highly skilled professionals with technologically advanced equipment.

GC mold is dedicated to developing and manufacturing quality, China plastic products, and services which consistently exceed customer’s expectations and span from concept to design to product fulfillment.

With experience in a variety of custom molded products and a specialization in high tech products, our commitment to quality, communication, schedule and lowest cost of design makes 1st Tech the right choice for your project no matter what the volume.

Molding Corporation offers:

  • Innovative Product Design Assistance 
  • In-house Tool Design, Build & Maintenance 
  • Rapid Tooling and Prototyping 
  • Competitive Pricing 
  • On-time Delivery 
  • Superior Customer Service 

Currently,GC Plastic injection Mold Company has fifteen (15) molding machines ranging from 15 ton to 650 ton with auxiliary equipment and is expanding to 36,000 sq. ft.  Operations are running 7 days a week, 24 hours a day.  The equipment is state-of-the-art Computer Aided Design stations, computer controlled tooling equipment and computer controlled molding equipment which allows for computer generated modeling of a design from concept to production to prove a design prior to fabrication.


Stereolithography is also known as 3D Layering and 3D Printing. Stereolithography is the process of turning CAD designs into real 3D objects in a matter of hours. 

In the past, it could take days, weeks, or even months to prototype a part using conventional methods. The design would have to be done, then the tooling on the molds would need to be finished. Stereolithography goes straight from design to the prototype. 

Stereolithography is a manufacturing process that uses a UV laser to create successive cross-sections of a 3D object within a vat of liquid photopolymer. A platform is placed on top of the vat filled with the polymer (an epoxy resin). Before the build begins, the platform is moved to a point just below the surface of the resin. As the solid state UV laser traces the layer in the polymer, the resin begins to cure; solidifying the part to be manufactured.

Stereolithography Machine

There are 4 main parts of the Stereolithography Machine:

  • Liquid Photopolymer Tank: holds serveral gallons fo the clear, liquid plastic.
  • Perforated Platform: the platform is immersed in the tank and can be moved up and down as the process is performed.
  • Ultraviolet Laser: transorms the liquid polymer into the 3D object.
  • Computer: controls the laser and movement of the platform during the printing process.

The photopolymer is sensitive to ultraviolet light, so when the laser passes through the polymer it hardens into each layer of the 3D object.

Stereolithography Process

The Stereolithography process is basically performed in the following way:

  • Create a 3D model with CAD software.
  • Stereolithography software slices up CAD model into many layers; about 5-10 per millimeter.
  • 3D printer (Stereolithography machine) “
  • The platform drops down into the tank layer by layer until the model is completed.

Stereolithography is not a quick process. It can take few minutes per layer depending on the size and number of objects being created. Typically it can take anywhere from 6-12 hours to complete one run. 

After designing your 3D object in the CAD software, it need to be modified to add supports to raise it off of the platform slightly. The SLA machine will render your object unattended. Once it is done, the platform is raised out of the polymer and your 3D models are rinsed in a solvent and baked in an ulta-violet oven to completely cure the plastic.

What can you make with stereolithography?

If you can design it with CAD, you can most likely produce it with stereolithography. You may need to add internal bracing to the 3D object so it will not collapse during the printing or curing processes. Once your object is made, you can actually test it out in an application, such as parts that fit on a motor or other machine. Of course, these parts won’t be used on a real machine, but they can accurately display if the parts will fit or not.

Stereolithography Costs

Stereolithography is not cheap. The photopolymer plastic can cost hundreds of dollars per gallon. The SLA machines themselves cost hundreds of thousands of dollars. The machines have to be vented because of the fumes the polymers and solvents create. For these reasons you will usually only find stereolithography machines in large companies. 

Some companies do offer SLA services at hourly rates though. This allows smaller companies to take advantage of the great benefits of steolithography without having to purchase such expensive equipment. 

These high costs are greatly offset by the turn-around time of making prototypes. Stereolithography is considerably faster than machining the test parts, and in today’s world, time is money.

Patented Gearing Technology

Palo Alto, CA—Ikona Gear International, Inc., headquartered in Coqutilam, British Columbia (Canada), has integrated its patented gear designs with high-temperature plastics to develop gears of plastic molded parts for engines and winches. Described in a recent analysis entitled, “Advances in High Temperature Resistant Plastics for Use in Motors & Gears,” the innovation was recognized by Frost & Sullivan as the winner of the 2005 Technology Innovation Award.

Ikona Gear received the award in July at Frost & Sullivan’s Excellence in Emerging Technologies Banquet, an annual event held in Boston to honor companies for pioneering the development and introduction of innovative technologies into their markets. The event recognizes the overall technical excellence of a company and its commitment towards technology innovation.

Ikona needed to design the tooth form in order for its gearing technology to qualify as a new invention. Because of a very high contact ratio and no tip interference, the Ikona gear teeth pair is reported to have zero backlash. Although most of Ikona’s earlier testing was done with standard stock metal, several partners—such as Aircast and Magna International—proposed the fashioning of gear assemblies from plastics. While most of this interest was driven by cost considerations, the Ikona gear profile is said to uniquely solve problems introduced by the characteristics of plastics.

“The Ikona gear design is more rigid, has a much higher contact ratio than standard planetary gear designs, and has lower friction as the gear rolls through its contact range rather than sliding with friction,” said Michael Valenti, research analyst for Frost & Sullivan. “This solves some of the problems with plastics being used in gearing.”

Ikona recently announced a development agreement to provide StarRotor Corporation, Houston, with its patented plsatic molded gear technology for third-generation StarRotor engines. According to the agreement, Ikona will incorporate its gear into the main drive mechanism of the StarRotor engine.

“This project will demonstrate the progression of technology from metal gears to high temperature plastic gears,” notes Valenti. “Ikona hopes to show that it provides a combination of the highest efficiency, compactness, strength, and the best sealing method of transferring energy from StarRotor’s engine into its main gear drive.”

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The Ikona applications will have to be further refined into a high-temperature plastic solution that can eliminate the need to introduce tolerances for metal expansion. Nevertheless, the company has already developed bold new gearing designs that will drive the use of high-temperature plastics.

This report includes information from wire reports.

Flat Grinding Work

Oak Creek, WI—Columbia Grinding has kept a steady eye on the future while working to establish its reputation as “Flat Work Specialists™. Over the years, the Oak Creek, Wis., job shop has consistently expanded its repertoire of grinding, lapping, and honing services. Today, Columbia Grinding applies its services to a long list of products, including stampings, machine parts, and molded foundry products, such as powdered metal parts. The company works with an equally wide array of materials that include basic metals, high alloys, and plastics, molded plastic parts etc.

After adding flat honing/grinding technology to its production operations in April, Columbia Grinding is now able to provide ultra-flat finished surfaces on metals, alloys, and other materials. The firm’s newest capabilities augment an already extensive offering of Blanchard, surface, and double disc grinding services.

“We cover a large spectrum, from large roughing jobs with relatively open tolerances to very fine finishing of small parts,” says Richard J. Lussier, president. “On our new Flat Honing/Fine Grinding machine, we can hold +/- 1 micron on a given load of parts and hold flatness across a part of 1 light band (one eleven millionth of an inch). Depending on the material, when asked to, we can generally hold a 4Ra [surface finish].”

The majority of the company’s equipment is dedicated to flat work jobs. Columbia’s seven Blanchard grinders are used for “the rough and big projects,” Lussier says, while four surface grinders are dedicated to tool room work and production jobs. For high-volume work, the company counts on its seven double disc grinders, which cover the three basic styles of double disc grinding: feed-through, reciprocating, and rotary carrier. The firm’s lapping department comprises six machines: three single-sided, two double-sided, and a 705 Stahli two-sided Flat Honing/Fine Grinding machine, the firm’s newest.

“Most of our work is 2nd or 3rd tier, but we do deal with some OEMs directly,” Lussier discloses. “We do work for a lot of different industries, from automotive to agricultural to the medical field. We do a lot of work for machine manufacturers. We even do work in the area of consumer products.”

Although technology plays a huge role in the company’s day-to-day operations, Lussier knows that there’s more to a company’s success than the depth of its equipment list. He credits Columbia’s attainment of ISO 9001:2000 certification as a key to much of the company’s growth and innovation.

“As we grew, we found that to sustain that growth, we not only needed new machines and processes, but also needed a management system to aid in that growth,” he commented. “Our ISO program gave us that management system. We have found that ISO provides the basics that allow our personnel the opportunity to be innovative. Today, you will find a machine on our floor that holds [a tolerance of] +/- 1 micron because of that system.”

Lussier told of an instance when a customer was line boring 5 small connecting rods at a time. The first operation after forging and heat treating, he said, was to grind the faces.

Today Plastic Injection Molding Companies are service 80% of customers on the world, who needs die casting or plastic molding parts, come to China and find a partner will be the best options to increase their business.

“We were double disc grinding to flatness tolerance of 0.001-inch, which we were holding with no problem,” he recalled. “The customer would then line bore these parts. They then did a 100% inspection of this operation. They would reject 5-15%, most of which dealt with the line-up of the two bores.

“Through discussions with the customer, we offered a different process of double-sided lapping. We did an experiment and were able to hold a flatness of 0.000011-inch. The most striking benefit was the parallelism control; we were able to hold 0.000020-inch. This allowed them to clamp these parts with no distortion and, thus, the line bore issue was put to rest.”