China Plastic Injection Molding  
China Plastic Injection Molding: Company Introduction Benefits of China Plastic Manufacture Why Chinese Plastic Products are Cheaper Tooling for Injection Molds Quotes for China Plastic Production Custom Plastic Manufacturing FAQ Plastic Parts from China - Contacts
China Plastic Injection Molding

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Molding Specialties
Rapid Tooling
Export Tooling
High Precision
Automotive
Blow Molding
Co-Injection Tooling
Rubber Molding
Medical Parts
Metal Die Casting
Metal Stamping
Technical Ceramics
Rapid Prototyping
 
What Some of Our Clients Say...

"First off, I would like to say that it is a pleasure to work with you and Bill of the Titoma organization. You are prime examples of what it takes to make a company a world class end to end manufacturing organization that meets or exceeds needs of its customers. Hats off to you and your owners!"

- Russell Huffman, New Tech Alarms

"I am honored to testify as a satisfied customer. I'm very happy with the work you did during the manufacturing phase, and especially grateful for the attention you gave me during the whole process."

- Edgar Orozco, AVICORVI SA

"We decided to work with Titoma because of their reputation and competitive price. We saved up to 100% higher on NRE (Non Recurring Expenses, i.e. design and molds) and 50% on parts. They delivered full turnkey development with impressive professionalism and quality. We have further products lined up for the coming year, and we will look forward to working with Titoma again."

- Michael Jones, Nigami Enterprises

"I recommend Titoma as an excellent partner for die-casted and injection molded parts. During the whole process we had very fast communication, and Titoma offered many useful suggestions on how to improve our mechanical design to avoid problems. The resulting parts were beautiful with a nice finish, and they managed to achieve the tight tolerances we required."

- Jacek Rydzewski, Grupa Techniczna

"We used to buy our custom made keyboards directly from a factory in Taiwan. Unfortunately, working with them turned out to be a major headache--endless shipping delays, which cost us a lot of customers. Two years ago, we asked Titoma to select and manage a new factory. Having a team on the ground that really understands quality and is able to make decisions on the spot saved us a lot of time and hassle."

- Henk Smit, BNC Distribution

 
 
 
 
 
 

Tooling for Injection Molds

Overview:

  • Parts Design (client may provide completed 3D files)
    The tooling process begins with a completed and checked part design. Titoma can optionally optimize your design for Design for Asian Manufacturing (TM) before tooling in order to lower your costs and ensure that your design will work well with Asian processes.

  • Parts Prototyping (if necessary)
    If you would like to validate your parts design with a machined piece that you can see and feel, Titoma can use Computer Numerical Control (CNC) techniques to prototype your parts.

  • Tool Design
    At this stage the tool is designed, using the information from your completed Tooling Information Worksheet.

  • Tool Check and Mold Flow Analysis
    The tool design is validated for correctness.

  • Tool Fabrication (including use of Computerized Numerical Control (CNC) and Electrical Discharge Machining (EDM) technologies)
    The tool is precisely fabricated according to the validated design.

  • First Shots To Client
    Once the injection molds are made, the first test shot samples will be sent out soon after via international courier. Once sent, these usually take around 2-5 days to arrive.

  • Tool Modifications and Texturing
    At this stage Titoma completes the tool and makes any required changes to bring the tool into the approved spec. Changes made to bring the tool to spec (specifically excluding design changes, which are always charged for) are made free of charge by Titoma.

    At this stage, texturing also takes place, which is normally the last stage before mass production.

  • Mass Production Run or Export
    At this stage parts are produced and delivered to the customer, or the tool is released for export use.

Technical Topics:

    Molding begins with tooling.  No matter how good the design, if the tooling is not up to the task, the quality of the parts will suffer.

The Molding Machine

    Achieving consistent dimensions and quality requires up-to-date molding machines, operating to specifications, with precise position and pressure control capabilities. The basic construction of a molding machine is fairly straightforward:

    Material is fed in through a hopper into a screw and barrel where it is heated to a molten condition. The melt is then injected under high pressure into the mold while the mold is held closed with the high force of a toggle or hydraulic ram. The goal is to melt resin in a very uniform and repeatable fashion, inject it into the mold under very precise and repeatable pressure conditions, and hold the steel temperatures in the entire flow system very stable. After the molten plastic is solidified, the mold is opened and the gear is ejected. It then continues to cool in the open air.

    There are many handling and pre-processing requirements for injection molding materials. Engineering polymers quite often must be dried to a specific dew point prior to use. When parts are made, runners are formed that some shops regrind and put back in the melt. This quite often raises more quality concerns than the slight savings in material expense may justify, and CPIM uses only virgin material.

Injection

    The method of injecting the plastic into the mold is very important. In most cases the plastic should be injected under high pressure very quickly in order to maintain the good characteristics of the melt completely during injection. As the mold cavity fills, the injection pressure should be held at the same high value and the speed of injection slowed to maintain that pressure. At the moment when the part is filled, and the mold machine switches over from injection to a pack & hold condition, the plastic melt is held at the same high pressure. This pressure is held for as long as it takes to freeze the gates and achieve the highest weight possible for the molded part. Below is a graphic image of the pressure and fill patterns of a typical plastic molded part.

(Part is filled in 0.23 seconds)
Legend:

  • Magenta - Measured melt pressure
  • Green - Programmed injection flow speed
  • Yellow - Measured injection flow

Example of Tooling Process: Three Plate Tooling

    Three plate tooling means that when the mold opens, three plates are separated. Between two of the plates the plastic runner is ejected, and in the second space, the plastic molded part is ejected.

     Three plate tools allow parts to be gated in the interior region of its body, which means that parts are a significant step away from the turbulent region of injected plastic flow. Melt temperature and pressure profiles are more uniform which results in better molded part dimensional stability. These three plate tools must be made with very high precision, and the gear cavity should be replaceable since part shrinkage can never be completely known before the tool is used to mold the gear.

Precision Characteristics

     Runner and part configurations must be optimized for proper molding. Gate locations and sizes are also critical. Mold temperature control is extremely important. Every piece of steel in the vicinity of molten plastic should be held at a constant determined temperature. Usually the mold base should be insulated from the mold machine at its mounting points to prevent uneven cooling from the large steel machine platens.

     Designing part ejection is also quite important. Can pin ejectors be used without deforming the part?

Administrative Topics:

  • Payments
    Our normal payment schedule is 40% initial deposit, 30% on First Shot, and 30% on approval.

  • Timing
    For tooling, it usually takes 5 to 6 weeks from receipt of deposit funds for molds to be made, assuming that 3D files are correct. If you have a special urgent request, we can reduce the lead time to 3 weeks (additional fees apply).

    "T1" samples are the first stage test shot samples produced based on your 3D files. Depending on the original 3D design and complexity of the plastic parts, it takes usually one to two weeks, sometimes longer, to complete the test shot stage.

    Lead-time for production depends on parts complexity and tool and material requirements, as well as the quantities requested by the client. If you have a dead-line to meet, please let us know. We will discuss it with our factories to see whether it is possible to meet your date. Usually we estimate 2 weeks for orders of 10,000 units.

    Please contact us for details on exactly how long your project will take, as times (and project scopes) vary greatly.

  • Freight Forwarding

  • Shipment times depend on which shipment method is used (i.e. DHL, UPS, FedEx, TNT, air cargo or sea shipment).

    Our prices are quoted FOB China or FOB Taiwan.

    If you have appointed a freight forwarder, we can use your account and existing agreements for a nominal fee.

    If do not have a specific forwarder, we can provide names of forwarders we have worked with in the past.

    Based on our experience, depending on the final destination, it samples usually take about 2-5 days via international courier, 2-5 days by air and  20-45 days by sea.

    When deliveries are sent FOB China, international courier service is not usually recommended as procedures can be complicated. EMS is an alternative for small quantity if the delivery is urgent, however.

    Additionally, standard times for custom declarations vary from country to country. Please check with your local freight forwarders service.


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