ABS properties:
1. Good combination properties, high impact strength, chemical stability and excellent electrical properties;
2. Good weldability with organic class, which can be made into bicolor plastic parts. Its surface can be chrome-faced or sprayed.
Common problems and solutions:
1. Sliver wire:
It is the most common problem of ABS material, which is also called crazing, water spot and so on. It is filiform strip phenomenon happened in the product surface, which is disturbed by gas: A. Air: air involved in during melting and ejection; B. Water: the material itself has water; C. Pyrolysis gas: Gas produced by hydrolysis or thermolysis.
Solutions: first, inspect whether the material is dried enough or not, and then adjust shooting technique to improve this problem. Poor sliver wire has some relations with mould exhausting.
2. Flow trace:
It is caused by the bad mobility of materials during injection. It is different from sliver wire, which is caused by water or material decomposition.
Solutions: increase the temperature of materials to improve mobility. Appropriately improve mould to increase its mobility and reduce injection speed.
3. Shrinkage cavity and dent:
Shrinkage cavity is caused by the filling of materials inside the mould is inadequate.
Solutions: increase the temperature of materials to improve mobility and extend injection dwell time, increase injection pressure and speed. You can also enlarge the size of sprue and heat it to eliminate shrinkage cavity.
Dent is produced by inappropriate material temperature and product design. Low temperature will not only causes shrinkage cavity, but also dent problems. High temperature will result in excessive shrinkage and produce dent.
Solutions: adopt appropriate process methods and increase injection speed.
4. Buckling deformation:
Plastic parts buckling deformation is due to the unreasonable parts design, gate location and injection molding processing conditions, which causes internal stress, uneven or excessive shrinkage. High or uneven mold temperature may result in difficult demoulding parts, and uneven cooling also can produce buckling deformation.
Solutions:
1) Process technique: lengthen injection molding circle, reduce its temperature, adjust injection pressure and temperature, slower ejection speed, enlarge its area and keep its balance;
2) Design: increase wall thickness, add reinforcing rib and reinforcement at circular bead, so as to avoid buckling deformation.
5. Stripe:
It is usually caused by melt fracture due to high speed injection;
Solutions:
1) Forming technique: increase the temperature of material and nozzle and reduce injection speed;
2) Mould: increase mould temperature, enlarge sprue size and change its shape.
6. Pocking mark:
Solutions:
5) Add dispersing agent or oil, increase temperature and back pressure;
6) If it is the mould problem, try another one;
7) Enough backing temperature and time;
8) Adjust mould temperature.
