There are numerous issues for being aware of when buying used plastic injection molds in order to minimize production problems associated with using the second hand molds. There are some potential production difficulties with second hand molds that include poor part quality, slow cycle times, molding below full cavitation and constant machine stoppages due to poor part ejection.
Damage of molding machine: The serious issue to be aware of is damage of molding machine. Second hand plastic molds are possible to be in bad condition that is; not flat and square and due to this it causes platen wear, broken tie bars and broken toggle pins. Damage in machine will show up as part quality problems and issues of mold balancing. Below are some tips for buying quality used molds:
- You should ask to see the mold producing samples in person or by video link. It is the only way to get a perfect idea of cycle time and latest part issues of quality. You should get the mold shipped to your factory and must test it yourself.
- You must ask for the recent samples from all cavities. Each sample should be weighed and must measure all wall thickness. With this information you will get a perfect picture in to the condition of the mold. Immediate production problems can be caused if there is any variation in cavity weights or wall thickness, so allow for this in your planning.
- You should ask for runner sample if mold has a cold runner. This is essential to perfectly measure shot size. You should also measure the runner thickness and compare it to the part wall thickness. There will be difficulty to mold quality parts if a runner is too thin.
- You must ask for the photos of both fixed and moving sides of all the used injection molds that you are interested in purchasing. Images will give you more information about the latest mold condition such as any unusual wear patterns which could lead to incomplete part quality issues. Images also provide an idea of mold design as it influences mold maintenance requirements.
- You should ask for the specifications of mold material. The type of steels, aluminums or copper alloys used in mold construction heavily influences mold life and the ability to repair and modify the mold.
- Must ask for the age of mold as it will give some idea of the degree of possible future problems. It is obvious that an older mold will probably give more problems than a newer one.
- You can also ask for part drawings and mold design drawings as it makes it easy to modify or repair the mold. This is a vital point because without drawings your mold maker could have to spend time making his own drawings and this can get costlier.
- Must inquire who made the mold. If it had been made from an injection mold manufacturer with a good reputation then this will give some confidence in to the reliability and quality of the mold.
Above were all the measures to be taken before buying used plastic molds. I hope that all the queries have been cleared to you.