Molders and moldmakers tend to spend months designing and building hot runner molds and ensuring that they have an injection molding machine and a hot runner controller ready when the tool is sampled. Oftentimes the hot runner cable, the connection from the controller to the mold, tends to get ignored until the very end.
I have been in your shoes and I understand how that happens. After all, the mold, the press and the controller are the most costly and are in the critical path for getting the project completed.
When you are developing your hot runner process, don’t forget the importance of the hot runner cable. A properly designed cable will have the following features:
1. Machined Connector Pins
Never accept stamped pins! Stamped pins will not stand up well in the injection molding environment and are prone to early failure due to pin breakage. Specify solid, machined pins in your cable design.
2. Connector Pin Retention
Pins that are not retained securely are prone to early failure for pin push out. Make sure your supplier has a process that will guarantee zero pin push out.
3. Individual Wires
Specify that your cable supplier use individual wires run through conduit, not bundled, extension cord-type cables. Bundled, extension cord-type cables are less expensive to buy, but they won’t take the flexing in our severe molding environment and will eventually (at the worst possible time) result in open connections.
4. Wire Quality
Always specify 100 percent stranded wire for your cables. Solid wire costs less, but solid wire will break in the injection molding environment. Hot runner cables are subject to thousands and sometimes millions of flexes and movements. Set up people throw the cables around during set up. Let’s face it, hot runner cables get abused in the injection molding shop environment.
5. Conduit Gland
Specify that the conduit gland is securely attached to the conduit and is independent from the wiring. This will ensure a positive, secure connection and greatly reduce cable pull out.
Any system is only as good as its weakest link. Do not spend hours upon hours ensuring a good hot runner, molding press and controller and then have failure because you ignored your hot runner cables. Make sure you put a cable specification requirement together for your cable supplier when you purchase this critical piece of hot runner equipment.
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