Injection molding is one of the core businesses of Topworks Plastic Molding, and Injection molding department mainly works on injection molding and secondary operation.It aims to improve production efficiency, product quality and control production costs. It owns Exquisite molding technology, the leading mold maintenance technology, nitrogen molding technology and high-end automatic production. The company introduces 30 Japanese Toshiba and Haitian injection molding machine, tonnage: 40T to 2800T, to ensure the quality of products and capacity of the production.
- Different types of injection molding machines cater to different customer requirements (40-850T);
- Rich experience in injection molding, be good at OA, digital appliances, home appliances and industrial products manufacture;
- Various types of Injection molding, like horizontal injection molding, vertical injection molding and overmolding;
- The standard operation of production ensures the stability of production quality;
- Continuous optimization of product production cycle, improve production capacity;
- Understand the various needs of customers, and products exceed their expect.
- Spray: PU paint, rubber paint, UV paint, high gloss paint, leather, metal paint, and etc..;
- Printing: screen printing;
- Laser carving, plating, heat transfer,silk transfer;
- Hot melt, ultrasonic welding.
Plastic material we normally use:
- ABS(with glass fill)
- Polypropylene(with glass fill)
- Nylon(with glass fill)
- PBT(wih glass fill)
- PC(with glass fill)
injection moulding process
In the injection moulding process a relatively cold mould, shaped as the negative of the component to be produced，is filled under pressure by the injection of a predetermined quantity of heated and plasticized material. The injected material solidifies, and after a period of further cooling the mould is opened and the product removed.
The following illustrate the main phases of the process as carried out on a horizontal plunger type injection moulding machine The course of the material from granulate to the finished product as illustrated in these diagrams is as follows:
The granulate is loaded into the hopper of the measuring or dosing device above the injection unit. From the hopper, a predetermined quantity of material falls in front of the plunger. This charge of material is pushed forward by the plunger so that it is deposited，first on to the injection plunger and then, after withdrawal of the latter, in front of it.
As the injection plunger moves forward, it forces the material through the plunger guide into the heating cylinder In this cylinder which is heated on its outer surface by electric resistance- type heater bands, the material is brought to a state of thermoplastic melt. Even heating of the material as it passes through the cylinder is aided by a spreader inside the cylinder. This spreader, or torpedo as it is also known, forces the material against the hot inner wall of the cylinder.
As successive strokes of the injection plunger force the material through the heating cylinder it’s consistency changes until, at the front part of the cylinder, it is in the state of a homogeneous melt ready for injection. The melt is forced into the mould through the injection nozzle. This operation is also referred to as shooting \ while the speed of injection, which is regulated to suit the material being used and the component, is known as the shot rate.
The mould, which is clamped or bolted in position in the injection machine consists basically of halves; one member mounted on the stationary platen and one on the moving platen.
From the injection nozzle the material passes through the sprue bush in the nozzle or fixed side of the mould. It is then distributed to the cavities through interconnecting channels or ‘runners.When the cooling period has elapsed the mould is opened and the components (T) are ejected from the moving mould-half by means of ejector pins which, as the mould approaches the fully open position，are operated by the ejector tail striking the stroke limiting screw.
Thus, the injection moulding cycle may be divided into five stages, as follows :
- The measuring out, in front of the injection plunger, of a quantity of granulate equivalent to the capacity of the mould cavity or cavities.
- The melting of this material in the heating cylinder to a consistency suitable for injection.
- Injection of the melted material into the closed and relatively cold mould.
- Cooling the injected material to the point of solidification.
- Opening the mould and removing the product.
What information is needed for injection molding?
Injection molding is considered a “primary” manufacturing process. For that reason, here will not address the details involved in computing secondary operations and packaging costs. We will look solely at injection molding costs.
The following outline those items needed for calculating actual injection molding manufacturing costs.
- Material costs
- Raw material
- Recycled material
- Scrap allowance
- Estimated regrind buildup
- Labor charges (if not included in standard machine rate)
- Direct and indirect labor
- Straight time versus overtime
- Machine rate (hourly)
- Setup charges
- Scrap allowance and downtime
- Number of cavities in mold
- Minimum number of cavities allowed
- Cycle time per shot, in seconds
- Variable overhead (utilities, maintenance, quality control, etc.)
- Fixed overhead (rent, depreciation, salaries, etc.)
- Tooling charges (if amortized over product volumes)
- Initial mold costs
- Maintenance costs
- Volume for amortization calculations