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

Maintenance: Between Commissioning & Scrappage

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

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.

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.

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? 

Well, both the questions can be answered by a single word. Can you guys guess what that word is? If ‘longevity’ is the word which sprung up in your mind, then you are correct!!!

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. 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.

Types of Maintenance

Maintenance can be broadly classified into two types:

1. Preventive Maintenance (Time Based)
2. Corrective Maintenance (Condition Based)

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

Preventive Maintenance

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.

     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.

1. Daily Maintenance          

     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.

2. Weekly Maintenance

     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.

3. Quarterly Maintenance    

     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 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.

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

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

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.

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.