Apr 23/19

Injection Mold Maintenance: From Afterthought to Prevention

Injection molding is a big business. Experts expect growth in the injection-molded plastic market. They predict it to increase by over 5.7 percent until 2023 in the automotive sector.

If you want to make high-quality parts, then you need high-quality machinery. But repairing such machinery can become expensive over time.

How can you reduce these inflated costs and keep your machines running for longer?

The most simple answer is through a preventative program of injection mold maintenance. Prevention is better than cure, after all.

If you want to bring down your costs using maintenance, read on.

Why Is Injection Mold Maintenance Important?

Regular maintenance lets you spot potential failures before they happen. You’ll need fewer big repairs, which lowers your operating costs. Running a maintenance program helps prolong the longevity of your tools.

The molding process causes wear over time. You could end up with a build-up of material on the mold. Over time, that could cause defects in parts or even damage the tooling.

The high temperatures involved in molding also cause wear and tear every time a cycle runs.

By not running a maintenance program, you risk needing to pay for unnecessary repairs. And you face a downturn in the quality of what you make.

Better maintenance also reduces the usage of spare parts. It cuts the labor hours involved in repairs. That means lower scrap rates and less downtime.

Why ruin the quality of your manufacturing output by not maintaining your machinery?

Why Doesn’t Everyone Run Maintenance Then?

Fewer repairs mean less downtime in general. But you’ll still experience downtime while during maintenance schedules.

Manufacturers can lose $22,000 per minute during downtime. Not everyone is willing to stop machines running to maintain them.

You need to take employees off the task of making parts to run maintenance. While they’re maintaining, they’re not producing.

No one wants to risk their productivity. Manufacturing productivity even fell by 4.8 percent in Q3 2017.

And people might see maintenance as a best practice rather than compulsory.

But think of the end result if you don’t perform this maintenance. More rejected parts, which means running more production cycles. It costs more not to maintain machines.

How Do I Start an Injection Mold Maintenance Program?

Set up a process and a system that people have to follow every time. Don’t let people do things their way. Different team members will do it in a different way every time.

If you face resistance from staff, push back. They’re all used to following processes for modeling or simulations. Maintenance is no different.

The best way to start a new maintenance process is to take an inventory of your tool room. Take the opportunity to get organized so everyone knows what goes where.

Improve your documentation. Do you have a customized knowledge base for each mold in your inventory? If you don’t, create one. This will cut time in training new staff to perform maintenance tasks.

Know the weakness of each mold. Your maintenance plan should focus on that specific weakness.

Share knowledge between your employees to keep consistency in your maintenance routine.

A Simple Routine

Run a basic routine before and after every cycle. Have staff follow a checklist as they go. This simple routine:

  • minimizes downtime,
  • makes sure your parts hit their specs, and
  • prevents pointless damage.

Use a gentle solvent to clean any residue out of the cavities. Blow dust or debris out of more complex molds with compressed air.

Clean runners and sprues, not just the cavities. Inspect connectors and hardware like bolts or plates. Look out for signs of wear. Make sure they fit well.

Let the mold dry completely before storage. That stops the mold from rusting, which causes even more damage and failures.

Have staff sign off on this basic maintenance inspection. Keep a log of which molds get checked, when they’re inspected, and by whom.

It keeps your staff accountable. But it also means you can track problems before they happen.

A More Advanced Routine

Follow this routine every ten production cycles or so. You might extend that depending on the complexity of your molds.

Start off by preparing for maintenance. Make sure the mold has completely cooled before you run through this routine.


Disassemble the mold. Use nylon or plastic tools to avoid damaging the mold or press.

Remove tooling from mold plates and store it in plastic or wood trays. Arrange it carefully to help protect its edges.


You may already have issues with the mold, prompting maintenance. But you can check these areas as a matter of course even if maintenance is routine.

Focus on any known problem areas, paying close attention to the weakness of that mold. Make a record of wear to the mold so you can track its progress.

Run a mold positional analysis to check the balance of the runners.

Check for stress, particularly where the two halves of the mold meet. Whenever a mold doesn’t smoothly open and close, it creates friction.

This can lead to problems with malfunctioning ejector pins. Or parts of the mold wear away because the extra friction increases heat.

Check any pins, mechanism, or components. You’re looking for signs of damage, wear, or malfunction. If anything doesn’t look right, replace it now.

Fix Problems and Clean

Take any corrective action if necessary. The more you follow the simple routine above? The less action you should need to take during the more advanced routine.

Clean the mold and cooling channels. You clean after you’ve done troubleshooting so you won’t clean away evidence of a problem.

Such evidence includes corrosion, discoloration, vent residue, or galling.

Achieving uniform cooling makes sure you get the best quality part. It also improves cycle times.

Reassembly and Checking

Re-assemble the mold, following the correct processes and procedures. Run a final check. This is also a good point to make sure everything is lubricated.

Sign-off the longer maintenance check.

Final Thoughts

This might sound like a lot of unnecessary work. You may worry about productivity falling while machines aren’t running.

But early intervention cuts down on costly repairs. Balanced against downtime costs, an injection mold maintenance routine saves more money than it costs.

It also introduces a professional mindset in your staff. By caring for your machines, everyone is ultimately caring for the whole business.

If you’d like to work with a partner that takes maintenance seriously, why not contact us today?