Mould Lifecycle Management (MLM) – Preventive Maintenance

Continuing with our series on Mould Lifecycle Management, this 3rd article focuses on how we should maintain moulds. We discussed the inputs and efforts required during the planning and qualification stage in our previous articles. In case you missed them, you can find them here:

Mould Lifecycle Management – Planning

Mould Lifecycle Management – Commissioning

Where Does Maintenance Fit in the Mould Lifecycle?

Maintenance: Between Commissioning & Scrappage

After a successful commissioning trial, our mould is now ready for production.

From Commissioning to Scrappage: The Maintenance Window

Someone has rightly pointed out that there is birth, there is death, and in between there is maintenance. The same is applicable for any mechanical product. A mould is no exception. Any mould which is not correctly maintained, haunts the owner with the cost and hassles for repair, refurbishment, or even a repeat mould.

Pre-Maintenance Essentials: Three Things You Must Know

Maintenance Pre requisites

Before we move ahead into the nitty gritty of maintenance, here is a list of necessary precautions that precede maintenance operations:

Know Your Mould

Moulds might look similar due to their resembling layouts but the design differs for various components. As an owner, you need to understand the mould design thoroughly. After all, you don’t want to damage it during maintenance.

Consider all the circuits (electric, hydraulic and pneumatic) in the mould and understand the required actions for individual circuits while or before starting maintenance. For e.g. ensure that all electric connections are switched off before beginning the installation, maintenance, or repair works.

Suppliers must undergo mould training from a qualified mould maker.
They must also obtain a maintenance manual from the mould maker and study it in detail. The manual must highlight the required maintenance activity and how it should be performed.

Supplier should know the abbreviations used in the mould for cooling circuit, hydraulic or pneumatic networks, and the cavity layout numbering.

Know Your Maintenance Tools

Every tool is designed for a specific use.
Failing to use the correct tool may cause injury to the operator or damage to the mold and other components.

It is also important to have a Tool and inventory management for better productivity, reduce downtime of your workforce and cost associated with the same.

Know Your Workforce

A mould can have a simple design or a complex one. Therefore, mould maintenance is not always an easy task. Never underestimate the same.

To ensure correct maintenance, employ only qualified and experienced personnel.

Why Preventive Maintenance Is a Business Imperative

Durability: The Necessity of Maintenance

Once you have covered these points, we are good to go with the maintenance plan. But before that, let us answer a question that naturally arises in all of your minds – why is maintenance required? Or, on a somewhat different note, what would happen if the mould is not maintained correctly?

Extending Mould Life & Reducing Repair Costs

An investor would want the asset to last long with minimal maintenance costs and hassles. Any mould which is maintained regularly remains healthy. In the process, this extends the useful life of the mould compared to a mould which is not maintained correctly.

Timely maintenance also reduces the overall cost for repair or refurbishment in two ways. One, they extend the interval between repairs.

Avoiding Unscheduled Downtime & Delivery Penalties

Second, and more importantly, they avoid unscheduled downtimes that require extravagant emergency repairs. Such downtimes can also disturb your delivery timetable, possibly exposing you to financial penalties from the client.

The Two Types of Mould Maintenance Explained

Maintenance can be broadly classified into two types:

Preventive Maintenance (Time Based)
Corrective Maintenance (Condition Based)

This article deals with time-based maintenance and will be followed by an article on the other type.

What Is Preventive Maintenance (PM) and How Does It Work?

Preventive maintenance (PM) as the name suggests is regular and routine maintenance to avoid any unplanned downtime. A PM cycle needs to incorporate planning and scheduling to avoid any loss of supply during the mould downtime.

Preventive Maintenance Cycle

Such maintenance is based either on duration or the number of shots produced as it depends on the maintenance plan provided by the mould maker. Generally, PM is carried out after three intervals viz. daily, weekly, and monthly.

Daily Maintenance: Lubrication & Visual Checks

The aim here is to lubricate all the moving and accessible parts of the mould, and clean them. These include the mould surfaces that form the part while the mould is operational.

Suppliers need to check for any visible issues in the part quality or functioning of the mould and take necessary actions to mitigate the same.

Weekly Maintenance: Leakage Checks & Moving Parts

This type checks the injection mold for leakages at each water and oil connection, and eliminates them. Following steps are involved:

Check all movable parts for functionality and stability, and tighten the screws again, if necessary.
Move the stripper or ejector plate forward and clean the tapers and surfaces behind.
Visually check the mould for any abnormal signs of wear or damage.

Quarterly Maintenance: Full Disassembly & Deep Inspection

Quarterly maintenance disassembles the mould and inspects it for signs of wear, damage, loose components, and water leakage, followed by corrective action as required. Procedure includes:

Clean all mould components.
Clean water lines by removing any rust build-up (especially core and cavity inserts).
Clean and lubricate the wear areas with a light layer of grease or where permitted.
Ensure that all band heaters and thermocouples are properly functioning and secured in the correct position.

Mould Storage: An Often Overlooked Part of Preventive Maintenance

Mould storage is an important aspect of preventive maintenance. Moulds undertake demand based production. Some are operational 24*7. Others may be producing a seasonal product and hence in operation only for a specific period. However, your production plant must safeguard the mould functionality and part quality throughout the mould lifecycle. For this reason, mould storage comes under PM.

Steps to Take Before Disconnecting the Mould

For proper storage, undertake the following steps before disconnecting the mould from the machine:

Purge the hot runner of any corrosive resin by moulding polystyrene, polypropylene, or polyethylene.
Purge all water from the lines and leave them dry.
Install dust caps on all air, water, and hydraulic lines.
Wipe dry any condensate on the mould or moulding surfaces.
Spray a protective coating on all accessible faces and moulding surfaces.
Close the mould and install latches and lifting bar.
Install electrical connector dust covers.

Storage Measures Once the Mould Is Cleaned & Protected

Once the mould is completely cleaned, lubricated, and safeguarded against corrosion, initiate the following storage measures:

Place it on a sturdy skid / pallet to protect from water spillage.
Store it as a complete unit. If the mould is stored in sections, tie it down to protect the moulding surfaces from damage and accidental tipping over.
Shrink / stretch wrap the mould and its parts such as temperature controller, electric cable & other parts to avoid accumulation of foreign particles.
Store the last shot produced by the mould as a quality measure to understand if there were any issues observed when the mould was in production.

When Preventive Maintenance Isn’t Enough: What Comes Next

Preventive Maintenance: Necessary & Almost Sufficient

Now, all these measures minimize any risk or damage to the mould. But as we all know, there is a fatigue limit to everything. Issues do arise in the lifecycle of a product no matter how hard you maintain them.

What if a non-conformity is detected while conducting quality checks of a plastic part? Or the respective mold cavity is blocked by the supplier, slowly and steadily? Or suddenly the situation worsens and you, the mold owner, come to know of multiple blocked cavities, and get a request to buy a new mould?

We will look at this in our next article which covers corrective maintenance.

As a Mould Lifecycle Consultant, we have been in business for 15 years and are well versed in the maintenance aspects of plastic moulds. Get in touch with us at www.efficientinnovations.in for top notch professional services.

FAQ: Mould Lifecycle Management (MLM) – Preventive Maintenance

1. What is mould lifecycle management (MLM) in injection moulding?
   MLM refers to managing a mould from design and commissioning to maintenance and eventual scrappage to maximize performance and lifespan.
2. What are the key stages of a mould’s lifecycle?
   Planning, commissioning, production, maintenance, and scrappage are the main stages.
3. What is the difference between preventive and corrective mould maintenance?
   Preventive maintenance is scheduled and routine, while corrective maintenance is performed after a failure or defect occurs.
4. At what point in the mould lifecycle does maintenance begin?
   Maintenance begins immediately after commissioning and continues throughout the production phase.
5. Why is it important to study the mould maintenance manual before starting work?
   It provides correct procedures, preventing damage and ensuring proper maintenance practices.
6. What circuits must be checked before beginning mould maintenance?
   Electrical, hydraulic, and pneumatic circuits must be understood and safely managed.
7. What qualifications should mould maintenance personnel have?
   They should be trained, experienced, and knowledgeable about mould design and maintenance procedures.
8. Why is tool and inventory management important in mould maintenance?
   It improves efficiency, reduces downtime, and prevents damage from incorrect tool usage.
9. How does regular preventive maintenance extend the life of a mould?
   It prevents wear, reduces breakdowns, and maintains consistent performance over time.
10. What are the financial risks of skipping or delaying mould maintenance?
    It leads to higher repair costs, unplanned downtime, and potential need for replacement moulds.
11. How can poor mould maintenance lead to delivery penalties?
    Unexpected breakdowns can delay production, causing missed deadlines and contractual penalties.
12. What is covered in daily mould maintenance?
    Lubrication, cleaning, and visual inspection of mould surfaces and moving parts.
13. What checks are carried out during weekly mould maintenance?
    Leakage checks, inspection of moving parts, tightening screws, and wear assessment.
14. What does quarterly mould maintenance involve?
    Full disassembly, deep cleaning, inspection, and repair of worn or damaged components.
15. How is a preventive maintenance schedule typically structured — by time or by shots?
    It is based on time intervals or the number of production shots, depending on the mould plan.
16. How often should mould screws and movable parts be checked and tightened?
    Typically during weekly maintenance or as required based on usage.
17. What lubrication is recommended for mould wear areas during maintenance?
    A light layer of grease is commonly used where permitted.
18. How should a mould be prepared before being disconnected from the machine for storage?
    Purge materials, dry water lines, clean surfaces, apply coatings, and secure all connections.
19. Why should water lines be purged dry before storing a mould?
    To prevent corrosion and internal damage.
20. What protective coatings should be applied to mould surfaces during storage?
    Anti-corrosion sprays or protective coatings on accessible surfaces.
21. Why is it recommended to store the last shot produced by the mould?
    It helps assess part quality and identify issues before storage.
22. How should a mould be wrapped and stored to prevent contamination?
    Use shrink or stretch wrap and store on pallets to avoid dust and damage.
23. Why should hot runners be purged with polypropylene or polyethylene before storage?
    To remove corrosive residues and prevent damage.
24. What happens when preventive maintenance is not enough to keep a mould functional?
    Issues escalate, leading to defects, breakdowns, and the need for corrective maintenance.
25. What is corrective maintenance and how does it differ from preventive maintenance?
    Corrective maintenance addresses failures after they occur, unlike preventive maintenance which avoids them proactively.