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plastic mold maintenance

plastic mold maintenance

In order to maintain quality parts for most of plastic injection molding company in China  , plastic parts must be produced in quality molds. The best quality parts are produced from
precision molds. Molds, quite like cars, begin to wear with use and maintaining a tool is an investment in precision.

Proper plastic molds maintenance is a matter of attention to detail. As things begin to wear, they must be noted and attended to. This is a simple matter of keeping a molding log for maintenance as little things come up and performing periodic maintenance as the tool is run in production.

Procedure:

The degree and frequency of maintenance are determined by four factors.
1. Material: Aluminum or soft tools will suffer wear and tear in a shorter period of time than tools made of conventional tool steel. Molds made of hardened steel will last longer than those made of conventional mold steel.

2. Complexity: Molds with intricate mechanisms or parts requiring unreasonably high precision will require more maintenance than a simple two plate tool making a low precision part. Slides, lifters, internal cores, hydraulic and mechanical systems, hot runners, complex ejector systems or mechanisms with small, therefore weak, components all add to the maintenance schedule.

3.Molding material: Materials with high melt temperatures wear molds out quicker than those with low temperatures. Higher melt temperatures will expose the metals to more heat and enhance material wear. Filled materials are abrasive because the fillers are not liquid. Fiberglass, mineral fillers (Usually Mica), etc. are very abrasive to metal, they will tend to wash the mold steel away after thousands of cycles.

4.Abuse: Excessive clamp pressures, high injection pressures, jerking the mold open and closed, not lubricating the appropriate components,multiple ejection, crashing the mold closed or closing up on partially ejected parts are a sure road to increased maintenance for some plastic injection molding companies in China .

…Have a clean operation using well maintained tools and equipment.

5.1.4.2 Use soft or treated water in cooling systems.
5.1.4.3 Blow out or drain the tool when it is pulled from the machine.
5.1.4.4 Seal the work area and mold storage area from outside environment.
5.1.4.5 Have outside, filtered, positively pressurized air circulated in.
5.2 Maintenance Frequency.
5.2.1 Level 1: Every time-short run plastic molding– the mold is pulled from production or put back into production, Routine Maintenance.
5.2.2 Level 2: 20,000 cycles or nine production shifts for Inspection Maintenance.
5.2.3 Level 3: 100,000 cycles or every 10 production runs for General Maintenance.
5.2.4 Level 4: 250,000 cycles or half the anticipated life time volume, whichever comes first for Major Maintenance.

5.3.2 All water lines should be drained and blown free of all residual water to avoid build up of rust due to standing water. It is imperative that no water be trapped inside mold.
5.3.3 Check and assure all bolts, plates, clamps etc. are in place and tight.
5.3.4 Bag the last shot as an example of the typical quality of this run. Store these parts with the mold.

5.5.2 Any components missing or cavity blocked off should be noted and attended to. A sample from the blocked cavity should be retained for the mold maker to make repairs.
5.5.3 The mold should be washed with safety solvent to remove the varnish and build up from the molding process.
5.5.4 The vents should be checked for depth in a minimum of four clock-face places around the cavity face.

5.6.9 The ejector system is to be examined for proper alignment. If the ejector pin holes have become egg shaped it must be determined if they should be re-drilled and bored to a larger size and the existing pins replaced with over size pins.
5.6.10 Broken return springs, re-plating or re-texturing as a result of the material eroding the mold surface, replacement of gates or gate inserts, new runner blocks etc. must be analyzed and determined. Replace all springs after 50,000 cycles.

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