Knowledge Base Article

Threaded Inserts in product assemblies

Planet Proto uses self-tapping inserts when our customers need inserts in their plastic parts. Inserts can be added to any properly designed plastic part for a $1.50 per insert. When building your quote select the number of inserts you need for each part. Then upload your drawing that describes insert location. The Planet Proto staff will install the self-tapping inserts into your part. An insert location drawing is needed to assure the inserts make it into the correct boss or feature. Your insert location drawing should be saved as a .pdf file, then uploaded through the Planet Proto upload tool. Please make sure your drawing and its file name are properly labeled.

The metal inserts are designed to meet the need for holding power in thermoplastic and thermosetting plastics like Planet Cast assemblies. Inserts can be used in Planet PolyJet parts or Planet SLA parts. These materials are more fragile and require extra care when being inserted. A Planet Proto representative will contact you if your design looks like it is not appropriate for the inserts needed.

Planet Proto uses Yardley inserts. For more information on Yardley inserts visit:www.yardleyproducts.com/guidelines.php

Inserts are installed flush or below material surface. This causes the load to not be transmitted directly through the insert but to the surface of the boss or the material in which the insert is installed. This is especially important where vibration is encountered.

General Guidelines

Cored or machined holes should be the correct size for the insert used. If the hole is too large, there is a reduction in stripping torque and pull-out force. For optimum performance, the boss diameter should be twice that of the insert diameter. A larger boss diameter increases the stripping torque. Please consult our engineering department for specific recommendations on your applications.

Wider spaced external threads reduce installation torque

Especially efficient for brittle or weak plastics

Ideal Hole Preparation Guidelines
Boss Diameter = 2 x insert diameter
Insert Diameter
Hole Depth = 1.25 x insert length
Starting Hole Size – Refer to your design and engineering reference material.
Please remember you are responsible for your design and engineering decisions. These recommendations are provided as a helpful rule of thumb to facilitate your project.