Injection Moulding

The injection mould temperature depends on the crystallinity of plastic, the size and structure of plastic injection moulded product, the performance requirements, and other process conditions such as melt temperature, injection speed, injection pressure, plastic injection moulding cycle, and the quality of plastic injection moulded parts. For amorphous polymer, the melt solidifies as the temperature decreases after being injected into the mould cavity, but no phase transition occurs. The injection mould temperature mainly affects the viscosity of the melt, that is, the filling rate. Therefore, for amorphous plastics with lower melt viscosity and medium density such as polystyrene, cellulose acetate, etc., adopting a lower injection mould temperature can shorten the cooling time.

The injection moulding processing methods for plastic products for household appliances mainly include injection moulding, extrusion moulding, thermoforming, hollow moulding, lamination moulding, compression moulding, transfer moulding, foam moulding, casting moulding, inlay moulding, encapsulation, etc., among which mainly is injection moulding. In recent years, some new plastic processing technologies and new equipment have been widely used in the plastic moulding of household appliances, such as precision injection moulding, rapid prototyping technology, melt injection moulding technology, gas-assisted/water-assisted injection moulding technology, electromagnetic dynamic injection moulding technology and coating membrane injection moulding technology.

There may be cracks of the injection moulded parts during the injection moulding process, so what caused the cracks of the injection moulded parts? Let's look at these aspects:

Injection moulding process
(1) If the processing pressure is too large, the speed is too fast, the feeding amount is too large, the injection and the pressure holding time are too long, and then the internal stress will be too large, which will cause cracks of injection moulded parts.
(2) Adjusting the mould opening speed and pressure to prevent demoulding cracking caused by quickly forcibly pulling out injection moulded part.
(3) Appropriately increase mould temperature to make injection moulded parts easy to demould, and appropriately reduce material temperature to prevent decomposition.

Compared with other types of moulds such as stamping dies and die-casting dies, there 5 obvious features of injection mould making. The analysis given by ACO Mold is as follows:

1. The mould cavity and core are three-dimensional
The outer and inner shape of the plastic part is directly moulded by the mould cavity and the core. These complicated three-dimensional surface processing is relatively difficult, especially the moulding surface in blind hole of the mould cavity. If the traditional injection mould making method is used, mould makers are required to have high technical level, many auxiliary fixtures, many tools are required, and the injection mould making cycle is long.

Mobile phone cases are usually made of PC (polycarbonate) or PC+ABS materials. Because of the poor fluidity of PCs, high mould temperature and high temperature filling are usually adopted in the injection moulding for phone case. The gates adopted are usually point gates. When filling, it is necessary to adopt graded injection moulding, find the position of the gate and the switching position of VP (injection-holding pressure), which will be very helpful for solving the abnormalities such as gate gas marks and burrs.

The following are the key points of the moulding conditions for the mobile phone case, and the setting points of the moulding parameters such as the melt temperature, the mould temperature, the injection speed, and the back pressure are explained.

In the past 10 years, injection mould industry has been developing rapidly in China. ACO Mold located in Shenzhen China, is mainly engaged in a series of plastic moulding processing services, such as the mould R&D, mould making, plastic injection moulding etc. ACO Mold injection moulding factory manufactures a wide range of plastic moulds for various household appliances, computer products, communication products, power tools and CD, DVD, MP3, MP4, etc. The largest mould size that we can make is 2 meters * 1 meter, the most heavy weight can reach 8 tons. ACO Mold factory now has large imported CNC machines and other precision machining equipments, using the world's advanced graphics software design and processing system as technical support. The monthly production of moulds can reach 50 sets. If you are looking for China plastic moulding manufacturer, maybe you can contact us by email to see more plastic mould pictures.

ACO Mold - plastic injection mould manufacturer located in Shenzhen, China, established in 2000, mainly develops, designs and manufactures all kinds of plastic injection moulds, and provides one-stop services such as external injection moulding, spray coating, silk screen printing, pad printing, electroplating and injection moulded parts assembly. Our injection mould factories are in Shenzhen and Dongguan. We offer custom injection mould making and plastic parts manufacturing for global companies. We serve a wide range of industrial, including household application, auto, electronic, medical, agriculture etc. All in all, ACO Mold provide below service:

1. CAD design/mould flow analysis/DFM
2. Custom injection mould
3. Plastic injection moulding
4. Prototyping, low volume injection moulding
5. Painting, skill printing, assembly

If you don't know where to buy moulds for plastic injection and don't know how to choose an injection mould manufacturer, we look forward to receiving your email. To make a new injection mould, the first thing you need to do is 3D drawings, and then analyze how to make the mould (size, structure, materials, cost reduction and so on), the key is how to connect the injection mould supplier's engineers with your companies' demands. Like our injection mould factory, we worked well with German and British companies for five years. So if you have a new custom mould making project next time, you can send the drawings to us for testing.

Mould is the mother of industry. As the precursor of the mother of industry, the importance of mould steel to injection moulds is self-evident. And the injection mould cost is also derived from the mould steel, because the injection mould manufacturer also quotes the price of the mould according to the price of the materials that mould use, such as the material coefficient method: plastic mould = 6 * material fee.
Calculate with experience:
Injection mould price = material fee + design fee + processing fee and profit + value added tax + mould trial fee + packaging transportation fee

We all know that although product will make hand board for verification before development and it will not start the mould project until the product is ok. But after mould test, it is still inevitable to be modified. Whether injection mould manufacturers should charge the fee of mould modification? How should the product developer avoid mould modification and reduce the cost of mould modification? There is a difference between modifying the mould and repairing the mould. The mould repair is caused by the reasons of injection moulding factory itself, and the mould needs to be repaired. The modification of mould is caused by the reason of customer factors, the product design need to be changed etc.

What are the consequences of excessive number of injection mould trials?
The unreasonable design of the injection mould makes the number of trials increased, which increases the investment in injection moulds. In addition, it will also extend the injection mould cycle.
The best injection moulding process and suitable injection moulding machine are selected during the injection mould trial, and the physical properties of the plastic are fully understood, which can effectively reduce the number of injection mould trials, so choosing the good injection mould factory is very important!

There are many different ways to calculate the an injection mould price, but, they have one thing in common, that is taking efforts to make technical and economic indicators organically combine in order to produce mutual benefits. It will make the injection mould to have competitive prices from the valuation to offer, to contract and to the settlement price.

Empirical Calculation Method
Mould price=material cost + design + process and profit + VAT + tryout cost + packing and shipping cost. Usually in the ratio:

• Material cost: materials and standard parts accounted for 15%-30% of the total cost of the injection mould;
• Process and profit: 30%-50%;
• Design fees: 10%-15% of the total cost;
• Tryout cost: medium-sized mould can be controlled within 3% while small precision moulds controlled within 5%;
• Packing and shipping cost: according to the actual or calculated at 3% of the total;
• VAT: 17%.