Design Guide for Injection Mold

A mold consists of two primary components:
the injection mold (A plate)
and the ejector mold (B plate)

What is a straight pull injection mold?

A part that can be made with a straight pull mold has all its features designed so that when the two halves of the mold pull straight away from each other. Undercuts on the part require mold pieces to pull out sideways, perpendicular to the direction of pull. These are called side actions.

Rib Design
Avoid deep & thin ribs if possible. Deep ribs require draft and clearance in order to allow the milling tool access. The max tool lengths average between 8-12 times the tool diameters. Also worth noting is that deep, thin ribs tend to increase the mold milling time and make hand polishing difficult and time consuming.

Draft
Include sufficient draft. Draft facilitates the removal of the part from the mold. The guidelines associated with the number of degree of draft required will vary with geometry and other part characteristics (e.g. surface texture requirements), but in general the more the better.

Injection Mold Design Center

Supported CAD Formats
• IGES (.iges) The Initial Graphics Exchange Specification (IGES) (pronounced eye-jess) defines a neutral data format that allows the digital exchange of information among Computer-aided design (CAD) systems.
• Sterolithography (.stl)
STL is a file format native to the stereolithography CAD software created by 3D Systems.
• Autocad (.dwg) is a CAD (Computer Aided Design or Computer Aided Drafting) software application for 2D and 3D design and drafting, developed and sold by Autodesk, Inc.
• Catia (.stp) is a multi-platform CAD/CAM/CAE commercial software suite developed by the French
company Dassault Systemes and marketed worldwide by IBM.
• PRO/E (.drw) Or Pro/ENGINEER is a parametric, integrated 3D CAD/CAM/CAE solution created by Parametric Technology Corporation (PTC).

Injection Mold Home

The key difference is how the molding compound is introduced into the mold, which affects flow patterns and glass integrity.

4000 RPM TOKUMI Machining Center

• Compression Mold
• Injection Mold
• Injection-compression Mold
• Thixo Mold

Slow feeding NC wire cut machine (Sodick AQ 550L)

Different methods, what you can expect and what the process will accomplish.

A major step in product development. The information gained from the prototype part is used to refine the product to make it more functional, more useful, more user friendly or just more appealing to the end user. This may take many forms from material selection, surface finishes, geometry changes or changing the design concept.

The selection of the prototyping method is dictated by what needs to be learned from the prototype. It is unlikely the first edition of prototype parts will be satisfactory for marketing purposes. If that were not the case, there would be no sense in going to the expense of prototyping. Modifications to the design or materials should be expected and used to learn from.

Stereolithography (SLA)
A rapid prototyping process that uses a vat of liquid UV-curable photopolymer resin and a UV laser to build parts one layer at a time. SLA rapid prototyping is a great process for concept models, master patterns and tradeshow models.

Machined Plastic Prototypes (MPP)
A subtractive rapid prototyping process for creating plastic prototypes from production plastics. The material is removed from a solid block plastic using CNC technology. MPP parts are ideal for functional prototypes and end-use applications.

PolyJet
A rapid prototyping process that jets photopolymer materials in ultra-thin layers (16µ) onto a build tray layer by layer until the part is completed. Each photopolymer layer is cured by UV light immediately after it is jetted. PolyJet rapid prototyping is a great process for concept models, master patterns and tradeshow models.

Selective Laser Sintering (SLS)
A rapid prototyping process that uses a high power laser to fuse small particles of powder to build parts one layer at a time. SLS rapid prototyping is a great process for functional testing and for low volume manufacturing.

Fused Deposition Modeling (FDM)
A rapid prototyping process that uses a plastic filament of material supplied to an extrusion nozzle. The nozzle is heated to melt the material and can be moved in both horizontal and vertical directions. FDM rapid prototyping is a great process for functional testing and for low volume manufacturing.

Cast Urethane
The process of using silicone molds to create urethane molded parts. Silicone is cast around a master pattern (typically made from stereolithography rapid prototyping). After curing, the mold is then used to form a two-part polyurethane material in the shape of the master. Cast Urethane Molding is a great process for pre-production runs. and low volume manufacturing.

The above information is of a general nature and is intended for a basic understanding of one of the processes we use in the product development stage to help bring our customers products to market. There are exceptions to every process or method depending on the individual application.

RESIN PROPERTIES
Your selection of material will determine the performance of the part manufactured using injection molds. It is also important to how the mold will fill. To determine the properties of the most common resins used.
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INJECTION MOLDS & PROCESSES
What are the differences between compression, injection, injection-compression, thixomolding and transfer molding?

All of these processes require matched metal dies designed to be clamped under pressure. The key difference is how the molding compound is introduced into the mold.
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MOLD STEELS
In an age that demands high productivity in manufacturing there is no substitute for high quality injection molds in your molding processes.

Most of the steel that Total Solution Plastic uses in our injection molds is purchased is purchased from LKM (Lung Kee Metal), which is a very fine and reputable company traded on the NY Stock Exchange. Their quality has been compared to DME here in the USA. We also purchase from Moldmax and Uddeholm to mention a few…of course the ultimate decision is made by our customer.

MOLD DESIGN GUIDE
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PROTOTYPING
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INJECTION CLASSIFICATIONS
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Glossary of Terms

Google Sketchup will help you model or design you product

IDES provides a free search engine for plastic material datasheets called Prospector

Free online dictionary