In our industry, according to studies by the Institute for Plastics Processing almost 7% of the production time is due to damage to the plastic cosmetic mould. In the same study, it is stated that only 30% of plastic injection companies carry out preventive maintenance at fixed intervals and only a third of these (10%) carry out maintenance according to the history of the mold.

Based on these alarming data, this article presents 10 useful ideas for keeping molds in proper service condition.

1. PREVENTIVE MAINTENANCE SCHEDULE FOR PLASTIC COSMETIC MOULD

It must be recognized that in these times there are already companies in Latin America that are applying the preventive strategy. However, most are still supported by corrective or “fire” action, which is nothing more than the reaction to unanticipated interruptions that can cut demand production in half.

Moreover, adequately following each stage of preventive maintenance with scheduled and non-emergency shutdowns, plastic cosmetic mould allows for effective and constant production over time. All this is linked to the fact that having interruptions in the workshop and production schedule, the risk is low.

Otherwise, the failure will enter the waiting room for the machining center and technical resources, which has no consequences other than productive inefficiency and low profitability of the product.

2. COOLING CIRCUIT OF PLASTIC COSMETIC MOULD

Water treatment is a potential bottleneck that we must tackle. A cooling circuit must not only recirculate the water to keep the inlet and outlet temperature of the chiller controlled. The cooling lines for an injection plant must have an entire filtering system.

This allows reducing the oxide in the cooling channels of the plastic cosmetic mould as much as possible.

As a micro reservoir adheres to the wall of the cooling channel, a reduction in the diameter of the channels begins. It is easy to check the flow rate in the check valve system. Moreover, it comes between the molds, the waterline.  Here the pressure drop and the thermal difference between the inlet and outlet of the mold is easy to calculate.

Another functional method is to have the measurements of the start of the mold. It is to have a comparison pattern and to establish an accurate diagnosis.

3. DEEP CLEANING OF THE PLASTIC COSMETIC MOULD

This tip directly connects with the first point. It has already become a pure theme of the plastic cosmetic mould as an isolated control volume of the system. Each plant has its own strategy for cleaning molds. Moreover, this ranges from the classic to the application of high-tech equipment.

Moreover, the mold maintenance team must be very clear. Without this stage, the mold will lose its useful life and productive level. To clean the tempering channels, a jet detergent solution is common to mechanically remove oxide deposits that are not otherwise achievable due to their geometry.

There are several recipes and cleaning kits. However, the hydrochloric acid solution with corrosion inhibitor and diluted in water is a remarkable success in the industry. Despite being functional, the search for a more competitive product forces plastic cosmetic mould maintenance leaders to streamline their processes.  This translates into investment in technology.

Why ultrasonic mold cleaning is preferred?

Ultrasonic mold cleaning has advantages in:

• reducing maintenance times
• improving cleaning effectiveness
• reducing damage to mold components

This consists of immersing the mold in an electrolytic bath at 20 kHz.  This generates cavitation in the fluid. Moreover, it generates better removal of the adhered material without affecting the edges of the mold or affecting the coating layer of the same.

4. CHANGING CONSUMABLE COMPONENTS

For both technologies described in point two, it is important to be clear that nipples, screws, nuts, plugs, etc., are consumable components and large accumulators of deposits, therefore, with maintenance, new ones should be installed.

5. CLEANLINESS OF PLASTIC COSMETIC MOULD SURFACES

At the end of production, the plastic cosmetic mould must be free of any adhering plastic residue. It should be regardless of the type and quantity of material. For this, the chemical attack must be common which, depending on the aggressiveness of the polymer, will be more or less concentrated.

For this idea, it is also important to remove the lubricant residues from the moving side of the mold with a degreaser.

6. CHANNEL OR HOT RUNNER SYSTEM

In summary, after a demanding productive run, the thermocouples, cartridges, and heating bands should be checked with a millimeter to compare with the datasheet that is within the normal range.

This is a very specialized system that must be supported by the system supplier since assembly and maintenance training should be carried out with the delivery of the plastic cosmetic mould.

7. SLIDE GUIDES FOR CLEANING

In the moving half, the guides require particular care. On the one hand, it is important to clean with acid and resin-free lubricants, and, on the other, to check the cylinder seal level in case of having hydraulic actuators on the slides and inserts.

8. CONTACT BETWEEN NOZZLE AND MATERIAL INLET TO THE MOLD

This area is subject to high loads during operation. There is a free space where the material can flow and relieve pressure.

However, this burr must not exceed the limits; if this happens, the area must be correct or the temperature profile configured in the machine must be reviewed.

9. PROPER PLASTIC COSMETIC MOULD HANDLING

The problem of damage provided to the plastic cosmetic mould lies, especially in operating and assembly errors. This problem is also attributed to poor communication between the design and maintenance teams.

Everything clearly starts from the fact that each mold is unique and it is not correct to generalize the maintenance process. It must start from a general protocol. Moreover, each mold must have its resume documented and the workshop must have adequate equipment.  Hence, it allows the mold to handle correctly.

10. PLASTIC COSMETIC MOULD INSTRUMENTATION

The production documentation is useful. Moreover, it is to find out that there is a problem. Furthermore, the information available will be much more effective if we have a plant that really applies the concept of Industry 4.0.

This is possible by implementing sensors for temperature, pressure, humidity, flow rate, number of cycles, the exact time the mold was open, etc. in each mold.

This is the beginning of a plastic cosmetic mould, allowing establishing the cause and/or root of the problem, effective maintenance times of the mold, and making correct decisions in real-time.