When deciding to use a RIM moulding to house your electronics or enshroud your instrument or high value innovation, one of the biggest drivers is usually the ability to have organic shapes brought to life from the CAD screen, combined with internal details such as ribs, boss features to act as stand offs and threaded inserts to mount screens, metalwork and provide mechanical fastening capability. All of which give added value, reduce build lists and assembly time and generally improve quality, fit and function.
The image below shows a very simple example of a moulded PU casing and demonstrates typical boss feature designs along with brass inserts that can be incorporated 'in-mould' meaning no post fitting! This ensures the inserts will be accurately positioned and with good rip strength as well as saving time and money on secondary post post processing.
Inserts can be sourced in a variety of materials ranging from typical brass inserts for standard application through to stainless steel for medical and aerospace and plastic for specialist applications where the presence of metal is not ideal (e.g. MRI machine locations).
The type of inserts available are as varied as you can imagine; from standard thru inserts, top hats, blind inserts to prevent material ingress, through to the very secure and high rip strength Big Head fasteners - all of which provide different capability and functionality to the final part.
The well know brands include Tappex, TR Fasteners and PEM inserts and sizes range from micro size 1mm right up to 10mm as standard with specials available.
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Depending on the design, application and how the insert has been integrated into the part, will determine its ultimate rip strength and the amount of torque that can be applied. However, by using the moulded-in technique you benefit from the contraction process of the cooling/curing material. Take a look at the pull out and torque details on the Penn engineering site for the various insert types if you are looking for further guidance in this area
The image below shows examples of some Big Head Fasteners which allow a really strong 'key' between the fastener and the moulded material for high load applications.
If you have a project where with low volumes but require high quality parts and wonder if a RIM moulded case work or fascia would be beneficial and would be interested in understanding how to make the most of the RIM process, please do get in touch.