Of course you must have the necessary knowledge of fundamentals of mold design and mold making in order to use this tool to its full potential.

This video is very helpful for aspiring mold designers using Solidworks.

I received this email from PTC 2 days ago…

The latest version of CoCreate Modeling PE, the world’s first free explicit 3D CAD software, is now available.

Download it today, and get all the flexibility of our standard CoCreate Modeling 3D CAD system free for assemblies up to 60 parts.

New in CoCreate Modeling PE 3.0:

• Real-time explicit modeling
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• Dimension-driven design changes
• Support for Microsoft Windows 7
• And much more …

Are you interested in free 2D CAD?

I downloaded the installation file (about 42Mb) to give it a try. The installation was quick and easy. I have to send my email to activate the software.

The interface has a clean layout and it has a command line, much like Autocad. Unfortunately for me, I use a very different 2D CAD software at work.

Below are my observation about DraftSight.

• FREE download for everyone. Professionals or students.
• Performance is slower than my 2D CAD.
• Very Autocad like. Therefore, difficult to use… at least for me.
• LINUX version will be available later this year. This is good news.

I do not know for how long DraftSight is going to be free, so download it now.

Are you more interested in free 3D CAD tool?

7 Steps:

1. Calculate for the mold dimension using the shrinkage factor.
   • The shrinkage factor can be determined by resin material properties or by experimenting. For example the PBT has a shrinkage of 18/1000.
   • Compensate for the tolerance and other possible deformation.
   • Include the draft angle whenever possible. The draft angle should be within the dimensional tolerance.
2. Draw product drawing using the calculated mold dimension. Include the embossed texts if it is a part of the product drawing. It is a good idea to draw the embossed texts using lines and curves. If your CAD is capable of “reflecting a text” then you are in advantage.
3. Mirror or flip your product drawing. The mirrored drawing will be your mold drawing. Notice that the embossed texts were also mirrored and they became engraved text.
4. Decide and draw the gate location. Locate it away from small core pins to avoid damaging those pins during resin injection process. For our example, I would like to use “side-gate”.
5. Decide the parting line. Input the parting line changes if there are any. Parting line changes should be visible on the top view, draw that too.
6. Decide the ejector location. Divide the mold drawing as you wish or as your process capability would dictate. Consider dividing on gas vents.
7. You can then derive or trace your cavity and core drawings using your mold drawing as reference.

Part 1 – Requirements to start your mold design:

1. Check the injection machine where the mold is to be mounted. This will help you decide the size and structure of the mold for ease of installation and other factors. Important notes:
   • Locating ring size (or other positioning method)
   • Nozzle size
   • Method of clamping (Auto or manual)
   • Temperature control system
2. Determine the number of cavities and volume requirements. This will help you decide the material that you are going to use and other mold components that you will choose for cost effective design.
3. Determine the gate location and size.
4. Determine the location where ejector pin marks are prohibited.

Part 2 – Mold base layout:

1. Place cavities close to the center of the mold to minimize base size and runner length.
2. Ensure that the molded part remains on the movable half (ejector half) upon opening of PL to facilitate proper ejection.
3. Waterlines should be placed as evenly as possible to the contours of the cavity.
4. Use support pillars underneath the cavity pockets.
5. Use ejector guides for molds with small ejector pins and rectangular ejector pins.
6. Provide eye-bolt hole for ease of mounting and dismounting.
7. Install mold opening prevention locks on the operator side.
8. Establish pry bar groove on the corners of the mold parting line to facilitate ease of mold opening during assembly and maintenance.

By this time you may ask for the mold layout approval from the customer.

Part 3 – Cavity/core details:

1. Check material shrinkage. Locate portions (corners) for possible significant deflection and deformation.
2. Maintain uniform wall thickness.
3. Draft angle should be within dimension tolerance.
4. Divide core blocks to simplify machining and provide gas vent path.
5. Gate, small cores, and cores with shut-off fittings are better designed as insertable components for easy modification and repair.
6. Watch out for possible deformation of core pins.
7. Position the ejector pins on the ribs and other high strength locations. Ensure ejector balance.
8. Detailing/part drawing: Include all parameters needed for processing -material, quantity, surface finish/texture, dimensions, tolerances and many more. Do not assume the machinist understands everything.

Any design change and amendments to the mold must be re-approved by the customer or mold owner.

Few extras that could make your mold one step further in terms of quality:

1. Bevel edges. Whenever possible use machine to bevel the edges.
2. Minimize scratches on the mold base. Keep the work table clean.

This checklist may be updated regularly so I suggest you “bookmark” if you find it useful.

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It includes 7 tutorials: introduction, part modeling, sketching, drawing creation, patterns, assembly components, and re-using 2D files. When you finish the tutorials in one day you can have 29 more days to practice and familiarize with the software. If you are a mechanical engineer and you don’t have a job then try to study this CAD 8 hours a day. By the time the free license expires you should already completed 240 hours CAD training that you can add to your resume. Cool idea!