All Molders should have some form of mold maintenance program.  Regular mold maintenance can help your mold to last longer, to run with less interruptions, and will save you time, money, and frustration in the long run.  The amount and frequency of maintenance is determined by several factors: 

(Mold Material)  Aluminum or soft tools will suffer wear and tear in a shorter period of time than tools made of conventional tool steel. 

(Part material) Plastic materials that have fillers are especially abrasive and will tend to wash away the mold steel after thousands of cycles.  Also plastic with a high melt temperature causes more wear than those with low melt temperatures. Higher melt temperatures expose the mold to more heat and enhance material wear.  Some materials give off excessive of residue or even corrosive gasses requiring more regular mold cleaning. 

(Mold Complexity) Molds with intricate mechanisms or parts requiring unusually high tolerances will require more maintenance than a simple open & shut mold, making a low tolerance part. Slides, lifters, moving cores, hydraulic and mechanical systems, hot runners, complex ejector systems or mechanisms with delicate components all add to the maintenance required. 

(Abuse) Lastly, molds can be abused by excessive clamp pressures, high injection pressures, over-packing/flashing the part, 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 all sure to cause excess wear and tear on your mold.

The 1st kind of mold maintenance you can perform is to reduce in-house tool abuse.

Have a clean operation using well maintained machines and have the right tools

Do NOT use hard tools (screw drivers, hammers, punches, knives on ANY molding surface, parting, or shutoff surface.  (We recommend having "soft" tooling like rubber mallets, punches and pliers made from plastic, copper, or brass on hand to avoid damaging the mold)

Use soft or treated water in cooling systems. Blow out or drain the tool when it is pulled from the machine.

Avoid excessive clamp pressures, high injection pressures, and over-packing/flashing the mold. 

Don't operate the press in such a way that the mold is rapidly jerked open and closed. 

Lubricate the appropriate components

Take great care not to crash the mold closed or close up on partially ejected parts. 

Seal the work area and mold storage area from outside environment.

We recommend several different levels of care/maintenance:

Preventative: Every day, and every time the mold is pulled from production or put back into production

Inspection: Every 20,000 cycles (or every 10 days of production)

Maintenance: Every 100,000 cycles (or every 10 production runs)

Major Maintenance: Every 250,000 cycles (or half the anticipated life time volume)