塑胶产品注塑成型常见问题及改善对策(Plastic products injection molding common problems and improvement measures).doc
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1、塑胶产品注塑成型常见问题及改善对策(Plastic products injection molding common problems and improvement measures)Cooling the parts in hot water.3, how to avoid product dents and pores?Product dents are usually due to insufficient force on the product, inadequate material filling and unreasonable design of the product.
2、 The dents often appear in the thick wall which is close to the thin wall. The porosity is caused by insufficient plastic in the mold cavity, and the outer ring plastic is cooled and solidified, and the internal plastic shrinks to form a vacuum. Most likely due to the fact that hygroscopic materials
3、 are not dry properly, and that residual monomers and other compounds are present in the material. Determine the cause of the pores, as long as the observation of plastic bubbles in the mold when the instantaneous appearance or cooling occurs. If the mold appears when it is instantaneous, it is most
4、ly the material problem. If it is cooled, it belongs to the mould or injection molding condition.(1) material problems:Drying materialAdd lubricantReduce the volatile matter in the material(2) injection molding conditionInsufficient injection;Increasing injection pressure;Increase injection time;Inc
5、rease the total pressure time;Increasing injection speed;The increase of the injection cycle;The reason causing abnormal operation of the injection cycle.(3) temperature problemToo much material causes excessive shrinkage;The material is too cold, resulting in insufficient compaction;The mold temper
6、ature is too high due to mold wall material can be quickly cured;The mold temperature is too low, resulting in insufficient mold filling;Mould has partial over hot spot;Changing the cooling scheme.(4) die problem;Gate enlargement;Enlarge distributary channel;Increase mainstream road;Increase nozzle
7、hole;Improved mold exhaust;The balance filling rate;The filling material flow to avoid interruption;The gate feeding arrangement of WIP thick wall parts;If it is possible to reduce the wall thickness difference;The mold caused by abnormal injection cycle.(5) equipment problem:Increasing the plastici
8、zing capacity of the injection press;Make the injection cycle normal;(6) cooling conditions:The parts are cooled too long in the mold to avoid contraction from the outside and shorten the cooling time of the mold;Cooling the parts in hot water.How to prevent the product line (joint) product line is
9、usually due to low temperature, the pressure caused by small joints.The problem of temperature:The barrel temperature is too low;The nozzle temperature is too low;The mold temperature is too low;The seams of mold temperature is too low;Uneven temperature of plastic melt.The problem of injection mold
10、ing:The injection pressure is too low:The injection speed is too slow.(3) die problem: seams venting;The component does not exhaust properly; diversion channel is too small; gate is too small;Inlet diameter of three runner is too small; nozzle hole is too small;The gate is too far away from the seam
11、s, can increase the auxiliary gate; products are too thin and cause premature curing; core offset resulting in single edge thin; mold offset resulting in unilateral thinningThe parts in the seams are too thin, thick; filling rate is unequal; die filling flow interruption.(4) equipment problem:The pl
12、asticizing capacity is too small;The pressure loss in the cylinder is too large (plunger type press).Such material:Material pollution;Material fluidity is too bad, add lubricant to improve flowability.5, how to prevent product embrittlement, brittle products often due to material degradation in the
13、injection process, or other reasons.The problem of injection molding: cylinder temperature is low, increase the barrel temperature; nozzle temperature is low, raise it; if the material is easily degraded, then the barrel nozzle temperature will be lowered; improves injection speed; improves injectio
14、n pressure; increases injection time; increases full pressure time; mold temperature is too low to raise it; internal stress, reduce internal stress; parts have joint lines, try to reduce or eliminate; screw speed is too high, and therefore degradation of materials.The mold problem:The product desig
15、n is too thin;Gate is too small;The diversion channel is too small;The products increased reinforcement, round.The material problem:Material pollution;Materials are not dry well;Volatiles in the material;Too much material returning or too much feed in material;Low material strength.The equipment pro
16、blem:The plasticizing capacity is too small;Second, there are obstacles in the barrel, which leads to the degradation of the material.6, how to prevent discoloration of plastic discoloration materials, usually due to burning or degradation, and other reasons.(1) material problems:Material pollution;
17、Material drying is not good;There are too many volatiles in the material;Material degradation;Decomposition of colorant;The additive decomposition.(2) equipment problem:The equipment is not clean;Material drying is not clean;The environment air is not clean, and the colorant is floated in the air an
18、d deposited on the hopper and other parts;Thermocouple failure;The temperature control system is out of order;The resistance heating ring (or far infrared heating device) damage;The cylinder obstacle to material degradation.(3) temperature problem:The barrel temperature is too high to lower it;The n
19、ozzle temperature is too high to lower it.(4) injection molding:Reduce screw speed;Reduce back pressure;Reduce the clamping force;Reduce injection pressure;Shorten injection pressure;Shortening the total pressure time;The slow injection speed;We shorten the injection cycle.(5) die problem:Consider m
20、old exhaust;Increasing gate size and decreasing shearing rate;Increase the dimension of nozzle hole, main channel and bypass channel;Remove the oil and lubricant in the mold;Changing oil moistening agent.(6) in addition, polystyrene and ABS with high impact strength, such as internal stresses of pro
21、ducts, will also change color due to stress.7, how to overcome the product with silver markings(1) material problems:Material pollution;Materials are not dry;Uneven particle size.(2) equipment problem:Check the material cylinder nozzle flow system with or without obstructions and burrs to influence
22、the material flow;The salivation, using the spring nozzle;Inadequate equipment capacity.(3) injection molding:Material degradation, reduce screw speed, reduce back pressure;Adjust injection speed;Increase injection pressure;Lengthen injection time;Extended full pressure time;The longer the injection
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