Proper maintenance plastic extrusion blow molding machinery (plastic blow moulding machinery should be cleaned regularly, especially extruder screw and head) and keep blow moulding machinery, raw materials and workshop clean, helping ensure blow molding machine normally working.
(1) parison head cleaning. Keeping the parison head clean is an important prerequisite for blow extruding high performance products. Some polymers, during processing are degraded, especially if the processing temperature is high, or during intermittent blow molding, the melt stay in the storage tank for a period of time. In addition, blow molding grade polymer contains a variety of additives, the melting process will form by-products. These degradation products or by-products will accumulate in the head of the machine, so that the surface of the parison appears stripe, affecting the appearance of the product.
The flow path of the head streamlined or chromed can reduce the appearance of parison fringes. So that the inflated parison in the contact blow mold cavity when a higher temperature, may be appropriate to offset the effect of parison stripes on the appearance of the product.
The production process with copper, etc. to remove the aggregates in the die mouth and sometimes it can eliminate the stripes on the parison. If not, we must stop machine working to have a full cleaning . Here are some ways to clean up the head.
Manual cleaning method. Before removing the head, use an electric heater to heat it above the plastic melting point. Can not use acetylene flame to heat, because it will cause the head of the local overheating and warping, affecting the die and mandrel size and shape. After the stop heating, remove the heater, open the head. First with copper or copper beryllium scraper shovel to most of the melt, and then do the final cleaning with brass cotton. But also with high-speed air to remove the melt on the head, but still use the brass to wipe the already oxidized melt, and sometimes also use the grinding wheel or by heating to remove the melt. The melt on the thread can be removed with an anti-sticking agent.
Hand to clean the head to avoid scratching the flow channel, especially the die area.
This method of work, will be the head of the flow channel metal material damage, and often metallurgical damage. Use the following cleaning method to avoid it.
2. Solvent cleaning method. That is, by means of acidic or alkaline chemicals, organic or inorganic solvents to clean. The cost of the acid or alkaline chemical cleaning method is low, but the cost of the chemical is high, and the cleaning efficiency is low, and the metal is also corroded. Organic solvent cleaning efficiency is high.
Solvent cleaning method to set up recycling equipment, so as not to pollute the environment.
3. Ultrasonic cleaning method. This method is good cleaning effect, single equipment and chemical agents of the high cost, and there are corrosion problems, preferably for post-cleaning, remove the inorganic residue.
In addition, there are salt bath, oven or fluidized bed cleaning method.
(2) blow mold maintenance. Blow molding transparent container to a high degree of polishing blow mold cavity, the production process from time to time to polish once. Use a polish and a soft tissue to polish the mold cavity, so that a small amount of polishing agent penetrates into the cavity surface and then uses a clean tissue to polish until the mold cavity appears. Polishing should always change the tissue paper, so as not to scratch the mold cavity.
Bubble mold clip billet edge worn by the skilled mold workers to repair.
The shearing block on the neck of the blow mold and the shearing sleeve on the intake rod is the key part and must be kept in good condition and replaced if necessary. For example, when the cutting edge of the cutting block is unevenly worn, the molded container may leak at the time of use.
Blow mold cooling channel due to clogging or corrosion and affect the flow of cooling medium should be immediately cleaned.
Blowing mold guide pin and guide sleeve to regular lubrication, each work at least once a year to replace, to ensure that the two mold alignment, to provide mold life.
When the production or blow mold to stop the inventory, use compressed air blowing mold cooling channel, mold cavity to be coated with protective agent, so as not to be corroded.