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Archive for the ‘Cast Urethane’ Category

5 Urethane Design Tips

Posted on: October 13th, 2015 by The Technology House

When using cast urethane, it is important to ensure that your part is designed properly. If not, then the part may not mold properly, thus jeopardizing your part functionality and lead time. But do you know what some of the major design pitfalls are? Or what the major guidelines are you should follow?

Here are 5 simple design guidelines for you to follow.

Wall Thickness
The minimum wall thickness for cast urethane is .040-.050”.  Most parts on average have a wall thickness ranging from .080”-.160”.

Draft
Although it is more critical for injection molding, draft is not as a big of a concern for cast urethane.  At least one degree of draft is ideal for cast urethane, certain parts can be molded without draft.  Although, if your  intention is to injection mold the part, then design the part as intended for production.

Radaii
Use at least a  0.125” radius in corners in order to increase part strength and help material flow in the mold.  In addition, use at least a  .060” radii in the corners of bosses.  This will reduce wall thickness, yet still retain the part strength.

Lettering & Logos
Cast urethane can mold both raised and recessed lettering.  Regardless of which one you choose, make sure that the lettering and logo is at least .040” thick and raised/recessed at this same measurement.

Tolerance & Accuracy
Part tolerances for cast urethane are +/-.010” for the first inch, and +/-.005” for every inch afterwards.

By following these guide lines, you will be able to have your parts casted with better accuracy and less scrap.  Thus allowing you to get your product to the market faster.  Have an upcoming project?  Feel free to contact us to see how we can help you.  Don’t have an upcoming project?  No worries, feel free to gander at our other resources like our handbooks and photo libraries.

 

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When it’s Best to Choose Urethane Molding

Posted on: September 29th, 2015 by The Technology House

Urethane molding is used mainly for prototype, bridge, and lower volume production runs. The process by which urethane—or, polyurethane—molding is done is similar to other types of manufacturing such as injection molding. The big differences come in the overall cost and cycle time as urethane molding is a type of soft tooling manufacturing method rather than hard tooling.

How Are Urethane Parts Molded?

Creating cast urethane parts is a simple three step process. The first step is to create a master from the 3D printing process stereolithography, also known as SLA. The 3D printed master is then used to create a silicone mold. The silicone mold is then used to cast the urethane parts. This manufacturing process bears with it a lower cost and fast turnaround time than steel molds you would typically use with injection molding.

What Are the Benefits of Cast Urethane?

For those unfamiliar with urethane molding, there is sometimes a question of why. Why would I go this route when I could just do injection molding and be ready for a fully ramped up production style manufacturing? Well, there are a few reasons for choosing urethane molding over other methods.

  • Fast tooling turnaround—silicone molds can be produced and ready to shoot parts within days.
  • Material versatility—You are able to test out different materials in a silicone mold without sacrificing part geometry due to shrink
  • Applications— Urethane can be used during most aspects of the product development process.

How Can I Use Cast Urethane Parts?

Urethane molding is ideal for creating functional prototype parts, engineering verification of designs, alpha and beta builds, as well as pre-production and low volume production parts. The cost and speed of this manufacturing and prototyping method is what often appeals to manufacturers. Allowing a fast turnaround can bridge the gap when production is ramped up and deadlines are closing in quickly, but it allows provides for a faster to market strategy, especially in highly competitive fields.

If you’re interested in learning more about how polyurethane cane help your business, feel free to contact one of our project managers today.

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Durometer. Do you know what it is?

Posted on: September 16th, 2015 by The Technology House

Durometer describes the instrument used to measure hardness, as well as the material’s hardness. Durometer is measured by the depth of an indentation into the material under a standardized force. Softer material will allow a deeper indentation, while harder materials will allow the opposite.

Common scales used today in casting are Shore A and Shore D. Shore A materials are rubbers, while shore D materials are plastics. Durometers range in scales of 10 with acceptable tolerance of plus or minus 5 points. For example a shore 60 A material will have a lower acceptable limit of 55 A, and a higher acceptable limit of 65 A.

Durometer Hardness Scale

What does this mean for you? It is important to understand the look and feel of the various durometers so that you can determine which material is best for your application. In addition to having different feels, the materials will have different properties (i.e. shrink rates, demold time, gel time, etc.) that need to be considered before molding.

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