How long is the life of an injection molding tool? If you think about it, this question is not strict enough.

We all know that there are many factors affecting the life of injection molds, and there is no way to answer the question of how long the plastic injection mold life is when the conditions are not clear.

How is the life cycle of a mold measured?

Most expensive injection molds operate in harsh conditions, and while a good mold should last under the conditions it operates in, even the best molds will experience some wear and tear.

The plastic injection mold life depends on several factors, and a mold with a faster turnaround can complete more cycles in a day than a mold with a slower cycle.

Since the life expectancy of an injection mold is measured in exactly how many cycles, rather than by considering the run time of the mold, a mold that can complete more cycles in a shorter period will generally have a shorter life expectancy.

While a shorter life expectancy may seem like a bad thing, the difference between a mold with a fast turnaround and a mold with a slow turnaround is not necessarily significant. If both molds can complete approximately 250,000 cycles before breaking down, then both molds are equally good.

What mold owners should understand is that the life of a mold is measured in cycles, not in the amount of time the mold runs. This makes more sense because knowing how many parts a mold will produce over its useful life helps molders determine if a mold will be able to complete the expected output of a project.

Factors affecting the life of an injection mold

The end of the life of the injection mold, with a variety of factors, the main factors affecting the life of the plastic injection molds are the following.

Mold material

Mold life has a great relationship with its plastic materials, the larger the number of production, the greater the load on the material requirements for the work, which should be selected for high-performance mold materials with strong load-bearing capacity and long service mold life expectancy

However, it should be noted that the mold material in its production cost accounts for about 25% ~ 30%, so you can not just choose a good material, the load-bearing mold parts available slightly worse materials.

Mold structure

The structure of the mold has a great relationship with the life of the mold, and a reasonable structure can help improve the bearing capacity of the mold and improve the life of the mold.

Such the use of a reliable guide mechanism can effectively avoid the mold bite when closing the mold; Another example is the use of rounded transition to avoid stress concentration structure, which can make the mold can withstand strong molding pressure because the mold is most likely to crack from the stress concentration.

Therefore, the selection and treatment of mold structure are appropriate, and the life of the mold is very influential.

Mold processing quality

There are many parts of the mold, processing methods are different, mainly forging, cutting processing, EDM processing, heat treatment, grinding and polishing, etc.

This processing is likely to make parts injury and mold life, such as EDM cooling improper and microscopic cracks; in the heat treatment due to uneven heating so that the performance of the parts is different; forging due to improper temperature control caused by cracks within the metal organization; grinding and polishing are not enough so that the surface roughness of the parts is too large and residual knife marks, etc., the above defects on the mold wear resistance, anti-fracture ability The above defects will have a significant impact on the wear resistance, fracture resistance, fatigue resistance, etc., thus affecting the life of the mold.

Mold working condition

Injection mold in the work, frequently through the injection molding process of mold closing, locking, injection, holding pressure, cooling, mold opening, ejection, etc., in this process, need to ensure that each work mechanism is reliable and light, and flexible work.

For this reason, it is necessary to make the moving parts move without obstruction and have reliable lubrication, which requires the operator to pay attention to the maintenance and repair of the mold frequently to make it in the best working condition.

Equipment condition

The performance of the injection molding machine has a greater impact on the life of the injection mold, various actions of the injection mold are completed by the relevant institutions on the injection molding machine, if the injection molding machine in the mold clamping force is skewed, or too much force or inaccurate action, so that the mold collision or eccentric force, the mold will be damaged, and its life will be greatly affected.

Ways to improve the life of plastic injection molds

Mold life has always been an important factor in the profitability of injection molding process projects. If you can make the mold life reach the appreciation value more than the design requirement through reasonable methods, then the profitability of the enterprise will be significantly improved.

Reasonable setting of clamping force

It is very important to set the clamping force of the injection molding process machine correctly to improve the life of the mold, too high or too low clamping force will hurt the mold life.

If the clamping force is set too low, the high-pressure injection may exceed the clamping force and the mold will be opened or even damaged during the whole injection moulding process. If the clamping force is set too high, the injection molding machine will apply excessive pressure to the mold parting line, exhaust area, and mold parts, which will damage the mold.

To avoid these situations, the ideal clamping force for each mold set can be calculated using mold flow analysis or by using the following formula.

Clamping force = projected area x material clamping force factor x safety factor

where the projected area includes the product and the runner. The clamping force factor for the material can be obtained from the material properties table or by consulting the raw material supplier. The safety factor is selected according to the actual situation, which is related to the stability of the injection molding machine, the structure of the mold, etc. It is generally 1.5~2.

Low-pressure clamping setting

Set low-pressure clamping on the injection molding machine to protect the mold. Set the high-pressure clamping position to no higher than 0.05inch of the actual mold contact position. gradually reduce the low-pressure clamping pressure until the mold does not lock.

At this point, the clamping pressure will slowly increase, allowing the mold to gradually transition from low-pressure to high-pressure clamping.

In addition, set the mold close timer to 0.5 seconds higher than the actual mold close time requirement. For example, if the actual mold close time is 0.6 seconds, set the mold close timer to 1.5 seconds.

Reasonable mold opening and closing settings

The clamping speed affects the cycle time, but the faster the clamping speed, the better. This is because too fast a clamping speed can cause excessive wear or damage to mold components.

It is important to ensure that the transition from fast to slow clamping is smooth and that the slow clamping occurs before the pin and part fit. Make sure that the transition between fast and slow mold openings is also smooth and that fast mold openings occur after all products and parts have been released from the mold.

Proper ejector setting

Incorrect ejector mechanism settings can jeopardize mold life by over ejecting or by improper product ejection, which can lead to press problems and damage the mold

The part needs to be ejected correctly from the mold based on the amount of separation required for the actual product. Too much-ejected volume can result in too much pressure on the ejector pin. In addition to the ejected volume, the ejector pressure setting should not be too high and needs to be based on the actual product needs.

Reasonable hot runner setting

The method of starting and closing the hot runner can affect the mold life. An improper start-up can cause mold rise, resulting in the need for mold removal and repair. Manually operate the valve gate to verify that the settings are correct and in good working order before full production.

Export the material in the hot runner through the guide tray and measure its temperature to verify that the material temperature is as desired. The hot runner temperature should be reduced immediately during hot runner closure to reduce the risk of plastic material degradation.

Reasonable mold cooling settings

Excessive mold temperatures can adversely affect mold life, so limiting mold temperatures to the minimum required for acceptable part appearance is an effective path to improving mold life.

In addition, it is important to ensure that the temperature difference between the moving and fixed sides of the mold does not exceed 6 degrees Celsius. Temperature differences above this range can cause excessive thermal deformation between the two sides of the mold, resulting in poor mold opening and closing problems, leading to mold wear or damage.

Mold cleaning and inspection

The molds in the production environment should be inspected, cleaned, and lubricated at least once per shift. Signs of aluminum mold wear such as scuffing, parting line wear, burrs, and metal chips should be noted during the process.

Establishing a regular preventive maintenance schedule, keeping aluminum molds maintenance records, and reviewing recurring maintenance events to establish preventive maintenance frequency will help reduce unscheduled maintenance events.

Check that the slides are lubricated and that the slides are working properly. Watch for signs of brake failure and loose hooks.

Injection Mold Maintenance

Plastic mold proper maintenance is more important than plastic mold repair. The more often the injection mold is repaired, the shorter its life span; while the better the mold is maintained, the longer the injection mold life span will be.

Mold maintenance is mainly divided into three points

a. Plastic injection mold daily maintenance: various moving parts such as ejector pin, line position, guide pillar, guide bush refueling, mold surface cleaning, water transportation of the evacuation channel, which is the daily maintenance of the mold production.

b. Plastic injection mold regular maintenance: regular full mold maintenance including daily maintenance in addition to the exhaust slot cleaning, trapped gas-burning black bit plus exhaust, damage, wear parts correction, etc.
c. Plastic injection mold appearance maintenance: the outer side of the mold embryo is painted to avoid rusting, the lower mold, fixed mold moving mold should be coated with anti-rust oil, mold preservation should be closed tightly to prevent dust into the cavity.

Summary

There are many kinds of plastic mold hardened steel, involving a wide range of prices, from a few dozen to several hundred dollars, there are imported, there are also domestic, so their quality, characteristics, use of the environment are different, so the service life varies greatly.

In addition, plastic mold steel is made into a mold when the production began to calculate the service life, mold making manufacturing is from the design, processing, assembly, commissioning, and other steps before being put into use, so in the mold processing process due to the level of design and manufacturing process differences, mold life will also be greatly affected.

The decisive factor in steel quality, choosing the right steel mold is the most important. For example, with different injection materials, the corresponding mold steel will not be the same, such as high polishing requirements, corrosion resistance requirements, etc.

In addition, the origin of different quality will also be different, the general life of P20 mold steel produced by large factories in about 300,000 die times, 1.2738 mold steel 500,000 die times, H13 mold steel and 1.2344 mold steel usually in a million die times, you can choose to use a large factory or small factory steel according to the situation.