Injection mould is the most important molding equipment in plastic injection product processing. Its quality directly affects product’s quality. And, mould accounts for a large proportion in production cost of injection molding processor. Its service life has a direct impact on injection product cost. For this reason, it’s an important issue for injection molding processor to improve the quality of injection mould, keep good maintenance, and extend its service life.
Injection molded product processor changes mould very frequently, because of various products. After finishing a production cycle, mould usually will be stored until next production cycle. But some processors don’t pay enough attention to mould storage. During its storage, mould becomes rusty and its surface glossiness goes down. This leads to poor product quality and high rejection rate. Some moulds even cannot be used any more. Companies will need to invest a great plenty of money to buy new mould. It causes a great waste. As data shows, usage and maintenance take 15%-20% of mould service life. Service life of injection mould usually reaches 800000 shots. Mould with good maintenance abroad even extends its service life twice or three times. However, domestic companies neglect maintenance. Injection mould’s service life is very short, only equivalent to 1/5-1/3 those abroad. Short mould service life causes wastes in working hours and energy resource for steel processing. Its affect on product quality brought a loss of billions of dollars per year. Hence, maintenance for injection mould is very important.
Injection mould has high technical content, and various components. If the components’ maintenance is overlooked in use, it’s apt to damage and rusty phenomenon. The economic loss may be thousands of dollars, or even millions of dollars. So, pay attention to maintenance for mould in use, to ensure the long-term service quality of mould. Firstly, company should keep a detail record for every mould, including its usage, maintenance (lubrication, cleaning, rust protection) and damage. According to these, which components are damaged and the degree of wear will be found. These will offer information for discovering and solving problems, molding technological parameter, and product material, to shorten mould trail time and improve production efficiency.
Secondly, processors should test mould’s all functions and measure the dimension of molded plastic parts, when injection molding machine and mould are under normal operation conditions. The information can confirm the existing state of mould, finding out damages in cavity, core, cooling system, and parting surface. According to information offered by plastic parts, the damaged state and maintenance about mould can be judged.
Thirdly, focus on tracing and detecting the important components: the function of ejection and guiding components is to ensure the mould open and close movement and plastic part’s ejection. If any of them get stuck, it will cause production halt. Check whether ejector pin and guide pillar have any deformation and surface damage at fixed period. Once found, they must be timely changed. After finishing one production cycle, paint professional antirust oil on moving, and guiding components. Especially attention should be paid to protection for mould bearing portion with gearwheel and gear rack and elastic strength of spring mould, to make sure it always in the best working state. In addition, the cleaning of cooling runner affects production efficiency and product quality greatly. Over production time, scale, rust, sludge and algee are apt to settle on cooling channel, diminishing cooling runner section, narrowing cooling channel, greatly reducing heat exchange between cooling liquid and mould. This will increase company’s production cost. So the runner’s cleaning should be brought to the forefront. For hot runner mould, maintenance for heating and control system will prevent the occurrence of production difficulty, so it’s particularly important. After finishing every production cycle, band-type heater, bar-type heater, heating probe and thermocouple on mould should be measured by Ohmmeter. If there are any damages, they need be changed timely. Compare with the mould resume, and keep records, so as to find problems timely and make corresponding measures.
Fourthly, focus on mould surface maintenance. It has a directly affect on product’s surface quality. The key point is to prevent corrosion.After finishing mould productive task, choose different ways to carefully clean residue injection molding based on different plastics. Use copper bar, copper wire and professional mold cleaning agent to clean the residue injection and other sediments in mould and then make air drying. Never use solid objects like iron wire and steel rod to clean, so as not to scratch the surface, If there is any rust caused by corrosive injection, use grinder to grind and polish, paint professional antirust oil, and then store mould at dry, cool, and dustless place.
A mould under great maintenance can shorten the time for mould assembly and trail, and reduce production malfunctions. Thus the production will be running smoothly to make sure product quality and reduce the cost of rejects. This will further reduce company's operating costs and fixed assets investment. When next production cycle starts, company still can produce qualified products successfully. So, for processors of injection molded products in the current increasingly competitive market, a mould under good maintenance will lend a helping hand to the company.