BMC (DMC) moulding process

The preparation of BMC (DMC) is divided into two steps: ① First add the resin, colorant, mould release agent, part of the filler, etc. into the high-shear mixer to mix evenly, the mixing temperature reaches about 50 ℃, and then slowly add the remaining The filler is mixed and stirred evenly to prepare the resin premixed slurry; ②Add the premixed slurry to the Z-type reamer mixer or other mixers, add the dried chopped glass fiber, and stir for 10~15 minutes Then pour out the bulk material, squeeze it into strips and pellets with an extruder, dry and seal the package with polyester film, and store it for later use.

Points for attention in BMC moulding

1) Barrel temperature and mould temperature. During processing, BMC is required to maintain low viscosity flow for a long time at the temperature of the barrel. Generally, the temperature of the barrel should meet the low limit of BMC. The temperature of the barrel is generally divided into two or three stages of control. The temperature near the hopper is lower and the temperature near the nozzle is higher. Generally, the difference is 20~60℃, and the mould temperature is generally controlled at 135~185℃.

2) Injection pressure. Due to the poor fluidity of BMC, fast curing, and complicated mould structure, the injection pressure should be selected to be higher, generally 80~160MPa.

3) Injection speed. The increase in injection speed helps to improve the surface quality of the plastic parts, shorten the curing time but is not conducive to exhaust and increase the degree of orientation of the glass fiber. Therefore, lower injection speed should be adopted under the premise of ensuring the surface quality of plastic parts, usually 1.8~3.5m/min.

4) Screw speed and backpressure. If a screw-type injection moulding machine is used, the screw damages the glass fiber greatly when injecting BMC. In order to minimize the damage of the glass fiber, the screw speed should be selected at a low value, generally 20-50r/min. According to the viscosity of BMC, the use of low back pressure is appropriate, generally 1.4 ~ 2.0MPa.

5) Moulding cycle. Due to the different size and complexity of plastic parts, the processing time of each section is also different. The general injection time is 2~20s and the holding time is 10~20.
Please keep us in touch as below info, if you required.
Taizhou Huangyan MDC Mould&Plastic Co.,ltd
No.35-1 Qingfeng Rd, Huangyan North Industrial estate, Taizhou, Zhejiang, china 318020;
Website: compression mould

Advantages and Disadvantages of Compression Molding

Molding process of compression moulding is a kind of molding method for thermosetting composite materials. Put a certain amount of material into the compression mould. Under a certain temperature and pressure, the material is heated plasticizing in the mould cavity and pressurized to flow and fill the mold cavity to form. So what are the advantages and disadvantages of the molding process?
Its main advantages are as follows:
1. The product is not easy to deform when it is compressing molding and have good dimensional stability, high precision, good repeatability;
2. High production efficiency, facilitate the realization of specialized and automated production;
3. It can be formed the compression product with complex structure one time and simple operation;
4. High surface brightness, no secondary modification;
5. Low mold cost. It can be mass produced at low cost.
6. No gate, gate or runner, different from injection mold
On the contrary, the main disadvantages are as follow:
1. Compression moulding complex with long cycle.
2. Need person to operate, so that can’t achieve full-automatic.
3. It is difficult to control spillage and waste more. But when you master the molding process, you can continuously reduce the waste of materials
The compression molding process is an ideal choice when used properly. Although the cost of a single part may be higher compared to other technologies, it can help minimize the overall project cost.
Please keep us in touch as below info, if you required.
Taizhou Huangyan MDC Mould&Plastic Co.,ltd
No.35-1 Qingfeng Rd, Huangyan North Industrial estate, Taizhou, Zhejiang, china 318020;
Website: compression mould

Introduce to BMC mold

BMC mold compression molding is to add plastic directly to an open mold cavity with a certain temperature, and then close the mold, the plastic melts into a flowing state under the action of heat and pressure. Due to the physical and chemical effects, the BMC hardens into a plastic part with a certain shape and size that remains unchanged at room temperature. BMC mold compression molding is mainly used to mold thermosetting plastics, such as phenolic molding powder, urea-formaldehyde and melamine formaldehyde molding powder, glass fiber reinforced phenolic plastic, epoxy resin, DAP resin, silicone resin, polyimide, etc. Plastics can also be processed with unsaturated polyester pellets (DMC), sheet molding compound (SMC), prefabricated integral molding compound (BMC), etc.

BMC mold is a thermosetting mold. Compared with thermoplastic mold, bmc mold is irreversible. Products processed by thermoplastic molds can be recycled, reprocessed and reinjected, while products processed by thermoset molds cannot be processed once formed. There is no difference in the structure of the two molds. The difference lies in the processed material: one is a thermosetting material and the other is a thermoplastic material.

BMC is a thermosetting plastic, which is mixed with various inert fillers, fiber reinforcements, catalysts, stabilizers and pigments to form a sticky “putty” composite material for compression molding or injection molding. BMC plastics are highly filled and reinforced with short fibers. Glass fiber reinforced materials account for 10% to 30%, and the length is usually between 1/32 inches and 1/2 inches (12.5 mm).

According to different final application fields, the formulated composite material can accurately control the size, good flame retardancy and tracking resistance, has high dielectric strength, corrosion resistance and stain resistance, excellent mechanical properties, low shrinkage and Stable color. BMC plastic has excellent flow characteristics, insulation and flame retardancy, and is very suitable for various applications requiring precise details and dimensions.

Please keep us in touch as below info, if you required.
Taizhou Huangyan MDC Mould&Plastic Co.,ltd
No.35-1 Qingfeng Rd, Huangyan North Industrial estate, Taizhou, Zhejiang, china 318020;
Website: compression mould

Introduce to SMC molding process

The main raw materials of SMC are composed of SMC special yarn, unsaturated resin, low shrinkage additives, fillers and various additives. SMC has the advantages of superior electrical performance, corrosion resistance, lightweight and easy and flexible engineering design. Its mechanical properties are comparable to some metal materials, so it is widely used in transportation vehicles, construction, electronics/electricity and other industries.

1. Preparation before molding
(1) The quality of SMC sheet has a great influence on the molding process and SMC part quality. Therefore, it is necessary to understand the formulation of resin paste, glass fiber content, etc. before molding.
(2) Determine the shape and size of the sheet material cutting according to the structural shape of the SMC part, the feeding position, and the process. In order to prevent contamination by external impurities, the upper and lower films are only removed before loading.
(3) Familiar with the various operating parameters of the press, especially to adjust the working pressure and the running speed of the press and the parallelism of the table. The mold installation must be level, and ensure that the installation position is in the center of the press table. Before molding, the mold must be thoroughly cleaned and coated with mold release agent. Before feeding, wipe the release agent with clean gauze to avoid affecting the appearance of the SMC part.

2. Feeding
(1) Determine the feeding amount and feeding area. The size of the feeding area directly affects the compactness of the SMC part and the surface quality of the SMC part. It is related to the flow and curing characteristics of SMC, SMC part performance requirements, mold structure, etc.
(2) Feeding position and method. The feeding position and method directly affect the appearance, strength and directionality of the SMC part. Normally, the feeding position of the material should be in the middle of the cavity. For asymmetric and complex SMC parts, the feeding position must ensure that the material flow reaches the ends of the molding cavity at the same time during molding. The feeding method must be conducive to exhaust. When stacking multiple layers of sheets, it is best to stack the materials up and down.

3. After the material enters the mold cavity, the press goes down quickly. When the upper and lower molds coincide, slowly apply the required molding pressure. After a certain amount of curing, the molding of the SMC part ends. During the molding process, various molding process parameters and press operating conditions should be selected reasonably.
(1) The molding temperature depends on the type of resin, SMC part thickness, SMC partion efficiency and SMC part structure. Generally speaking, the forming temperature of thick SMC parts should be lower than that of thin-walled SMC parts. For example, if the thickness of the SMC part is 25-32mm, the forming temperature is 135-145 ℃. And thinner SMC parts can be formed at 171 ℃. It is generally believed that the SMC molding temperature is between 120-155 ° C.
(2) Molding pressure varies with SMC part structure, shape and size. SMC parts with simple shapes only need a forming pressure of 5-7MPa; SMC parts with a complicated shape can have a forming pressure of 7-15MPa. The size of the molding pressure is also related to the mold structure. The molding pressure required by the vertical parting structure mold is lower than that of the horizontal parting structure mold. In short, the determination of molding pressure should consider many factors. Generally speaking, SMC molding pressure is between 3-7MPa.
(3) The curing time is related to factors such as material type, molding temperature, SMC part thickness and color. The curing time is generally calculated at 40s / mm. For thick SMC parts above 3mm, each additional 4mm increases the curing time by 1min.

SMC Mold

The full name of SMC is Sheet Molding Compound. SMC is made of resin paste impregnated fiber or chopped fiber mat and covered with the polyethylene film on both sides. SMC belongs to the range of prepreg felt and is one of the most widely used molding materials in the world.
The SMC molding process is an advanced composite molding method, and the SMC mold is the basis of the molding process. Good product quality is guaranteed by reliable molds. Therefore, the design of the mold is particularly important in the entire SMC mold production work.
In the SMC mold design process, the mold cavity should be designed according to the specific dimensions of the product. In addition to this, it is necessary to select the appropriate material according to the surface quality requirements of the product and the size of the demand. In order to ensure product quality and process feasibility, the cutting edge and the ejection system of the mold should be designed reasonably. In order to make the product easy to demold, ensure product accuracy, strength and facilitate mold processing and other factors, the selection of parting surface should consider the following principles:
① In order to make the product easy to launch and simplify the ejection mechanism, the position of the parting surface should be such that the product can be left in the lower mold as much as possible after opening the mold;
② Minimize the damage of the flash to the appearance of the product, and at the same time, it should be easy to remove the residual flash;
③ It is convenient for mold manufacturing and mold parts processing;
④For products with high requirements for radial dimensional accuracy, the influence of flash thickness on product accuracy should be considered, and the vertical parting surface can be taken to ensure the product radial accuracy;
⑤Ensure the strength of the product and avoid sharp corners and thin walls.

China SMC mould manufacturer

As a professional SMC Mould manufacturer in china, MDC mould can provide SMC mould and low volume quantities of SMC molding service with our customers.

SMC Mould process produces high strength, complex parts in a wide variety of sizes. The SMC material charge is manually or robotically placed in SMC mould; the heated mold halves are closed, pressure can be available applied from 500T till 4000T at MDC workshop, cycle time ranges from one to five minutes, depending on part size and thickness. Features such as ribs, bosses and inserts can be molded in.

In-mold coating(IMC) and vacuum system in SMC mould are available to improve surface paint ability, eliminating the need for primer. Color compounds can be customized.

if anybody has urgent SMC mold or SMC Molding projects or delivery time pressure, MDC team will give them support, as all of our milling machines are working at 24 hours with 2 shifts.
Please don’t forget that we’re a professional compression mold maker and foaming tool maker. We will stay at your disposal. Please keep us informed, when any questions or requirements.

What is compression mold

Compression molding, used for compression mold, is a molding method according to the characteristics of each stage in plastic curing reaction, and often used to produce high-quality composite parts. Compression molding materials are usually powder, granular or fibrous plastic, such as thermoplastic(LFT, GMT,LWRT), rubber and thermosetting plastic(SMC, BMC), Or new composites(SymaLITE,carbon fiber).

What is compression molding process?
Firstly, plastic is put into the cavity at the molding temperature, then close the mold, the material inside the cavity becomes a molten state under the high heat and high pressure, and then fills in the whole cavity. After curing, the product is ejected by ejector, repairing the flash. For compression molding, material, shape, compression, temperature, part thickness, cycle time must be considered. You must analyze the characteristics of the materials to ensure the product perfectly. Molding cycle time is something with material, part feature, mold design, temperature, pressure, etc.

What are the advantages and disadvantages of compression mold?
Advantages of compression mold:
(1)The loss of raw materials, the wear of the mold cavity is small, and the maintenance cost of the mold is low.
(2)It can be used to form large flat products. High dimensional accuracy, small shrinkage, low internal stress, the mechanical properties are relatively stable. The surface is smooth without secondary modification.
(3)The cost of the molding machine is lower, the mold structure is simpler, multiple cavities can be produced at lower cost, and the manufacturing cost is usually lower than that of the injection mold.

Disadvantages of compression mold:
(1)At present, it is not suitable for molding complex products with depressions, side slopes or small holes.
(2)Burrs must be trimmed manually
(3)For thermosetting plastics, when the molded products have slight defects, they are often unable to be recycled.

What is compression molding used for?
Compression molding is widely used in industry, agriculture, automotive industry, electricity, chemical industry, construction and other fields. MDC has developed compression molds such as spoiler templates, fenders, bumpers, front panel on trucks, engine covers, doors, bottom fenders, car ceilings, seat backs, electric boxes and bathroom door panel basin, etc.

Compression mould

compression moldcompression mold

What’s LWRT Mold?

As a leading LWRT Mold maker, we’re pleased to introduce new technology named LWRT for somebody else.

LWRT means Low weight reinforced thermoplastics. This type of material has been widely used in underbody shield of Automotive industry. both for Interior and exterior parts.

LWRT composite sheets are typically thermoformed into parts with a desired geometry.
Thermoforming is a stretch-forming process resulting in a reduction of the sheet’s original thickness. The deeper the cavity of the geometry is designed, the thinner the wall thickness of the final part will be.
The formability of the sheet material is its ability to form into parts with desired geometry without failure. The geometry of the parts varies according to different applications, and some
applications have a very complex geometric design. A good example of such applications is trunk trim, which has a deep-drawn, multi-cavity geometry.

The advantage of LWRT material would be:

1.weight reduction of at least 25% compared to traditional technologies

2.acoustic performance satisfaction without need for additional sound-absorbing elements to be welded or over-molded per piece.

MDC Mould, as a professional LWRT Mold maker, has produced many molds for our customers, such as Audi, BMW, Daimler, Jaguar, etc.

Please keep us in touch as below info, if you required.

Taizhou Huangyan MDC Mould&Plastic Co.,ltd

No.35-1 Qingfeng Rd, Huangyan North Industrial estate, Taizhou, Zhejiang, china 318020;

What are the advantages of parting surface design?

In order to make the product easy to eject and simplify the ejection system, the position of the parting surface should make the product leave the bottom mold after the mold is opened;

  1. Reduce the damage of flash to the appearance of the product, and at the same time facilitate the removal of flash;
  2. Facilitate mold manufacturing and mold parts processing;
  3. For products with high requirements for radial dimensional accuracy, the effect of flanging thickness on the product accuracy should be considered, and the vertical parting surface should be taken to ensure the radial accuracy of products;
  4. Ensure the strength of the product and avoid sharp angle and weak walls.

It is very important to design the parting surface. The parting design should be carried out at the initial stage of mold design to draw the parting design drawing, so as to ensure the smooth demoulding of the product and facilitate production.

Please keep in touch with us, when any doubts on GMT Mould.

Taizhou Huangyan MDC Mould&Plastic Co.,ltd

Add: No.35-1 Qingfeng Rd, Huangyan North industrial estate, Taizhou City, ZheJiang, China, 318020

MDC mould, Compression mould

MDC in JEC World 2019

2019 JEC world was taken place on 12-14 March as scheduled. As the leading SMC/GMT mould manufacturer in China, MDC Mould always pay close attention to the changed and development of composites Industry.

In regards this composite exhibition, too many experts who have experienced in composite industry focus on the most advanced technology for Aero&Space, Auto&Transport, Construction&Energy, and introduce the discovery for the latest trends per industry. MDC keep to collect the information and growing up year by year

Please keep in touch with us, when any doubts on SMC/GMT Mould.

Taizhou Huangyan MDC Mould&Plastic Co.,ltd

Add: No.35-1 Qingfeng Rd, Huangyan North industrial estate, Taizhou City, ZheJiang, China, 318020;


MDC mould, SMC mould, BMC mould, GMT mould, Compression mould