How to choose LED thermal plastics reasonably

LED lighting fixtures, as a rising star in the field of lighting, have a promising future in the next five years and show strong growth momentum. According to the trend of decreasing LED lighting prices and increasing performance, the total cost of the entire life cycle of most LED lamps will be significantly lower than that of traditional lamps in the next 1-2 years, becoming the mainstream lighting source.

As the outer casing of LED lamps, aluminum alloys and ceramic materials have been traditionally used. In the past two years, the new materials of heat-conducting plastics have sprung up and become accepted by the majority of manufacturers, becoming a high-profile shell material.

To sum up, thermal plastics have the following advantages:

1. Insulation and flame retardant, high safety.

2. Light weight, the density is about two-thirds of aluminum.

3. Convenient processing and mass production.

4. No need for secondary processing, more environmentally friendly.

Faced with a large number of thermal plastics suppliers, how to choose a more cost-effective product, the following are some points worthy of attention:

First, reduce the scope of screening considerations

1. RoHS for thermal conductive plastic, UL certified

Whether it is RoHS or UL certified will be a key factor for the whole lamp factory exporting to Europe and North America. The RoHS, the UL certification authority, in fact, also did a preliminary screening of the material, which for many manufacturers, in the case of not familiar with the new material of thermal plastics, can be certified by the testing agency Learn more about thermal plastics. It is worth noting that the UL certification number can be queried through the network, and its authenticity is more credible.

2. Material processing equipment required

The properties of thermally conductive plastics are thermoplastic and thermoset. Most of the heat-conducting plastics are thermoplastic raw materials. Such materials can be produced by conventional ordinary injection molding machines. If the original manufacturer of energy-saving lamps has a large number of injection molding machines, it can continue to be used. Another customary practice is to outsource the injection molding process to a professional injection molding company. In the case of insufficient production capacity, it is easy to use the external factory to expand production capacity.

On the other hand, if the heat conductive plastic is a thermosetting material similar to phenolic resin, ordinary injection molding machines cannot be used, and a special thermosetting plastic injection molding machine must be used, and the extra equipment cost will greatly increase the cost. And once the production capacity of its own injection molding is insufficient, it is more difficult to find a suitable outsourcing injection molding plant.

From the practical point of view, the molding cycle of thermoplastic materials is shorter than that of thermosetting materials, which means that the processing cost will be reduced.

3. The color of the material

Usually, in thermal conductive plastics, certain substrates (such as PC, PPS, PA) are added with additives. These thermal conductive additives are usually dark materials, and the final customer demand is usually white, if not available. Qualified white materials may result in an additional painting process after injection molding, which increases costs.

4. Place of production of raw materials

In terms of current LED full-light export orders, the delivery date will be an important clause. If the heat conductive plastic is produced domestically, the delivery should have sufficient time to deal with it. Where the origin is overseas, it is usually necessary to consider shipping and customs clearance, the delivery time will be extended, and the cost of selling imported raw materials will also increase compared with the same in the domestic production.

Second, the comparison of material properties

Thermal conductivity

As a key technical indicator, the thermal conductivity of the materials of various manufacturers is currently the most concerned by users. The technical standards for testing thermal conductivity are different, including ASTM E 1530, ASTM E1461, standards defined by a certain company, and so on. Even under the same technical standards, the test methods are different. For example, there are plate method and laser method. In the case of different test methods, the error range of the final test results is completely different. Generally, the accuracy of the laser method is higher than that of the flat method, and the equipment involved in the laser method is basically dependent on imports and is expensive.

It is for these various reasons that the size of the thermal conductivity can cause the user to enter a misunderstanding. The more realistic approach is: injection molding the thermal plastics of different manufacturers on the same mold, and then assembling the same lamp and power supply. After power-on, test the pin temperature of the lamp bead or the temperature of the aluminum substrate near the pin. The temperature is low. It is a material with better heat dissipation.

In another approach, thermal plastics suppliers typically provide standard male mold products that can compare the heat dissipation of a male mold with a heat sink of the same size (such as an A19 bulb) to roughly determine the performance of the material.

2. Material mobility

Usually expressed by the melt index. The heat conductive material with good fluidity is easy to form and smooth in production. Based on the high thermal conductivity plastic, the wall thickness of the heat sink can be designed to be relatively thin, usually 1-1.2 mm. Due to the thin wall thickness, the heat dissipation path is shortened, thereby improving the heat dissipation effect. At the same time, the thinner wall thickness will reduce the weight of the material and reduce the material cost. If it is a poorly fluid material, it is usually not easy to be injection molded, and it will easily damage the mold and increase mold maintenance costs.

3. Mold shrinkage

Generally, under the condition of a thickness of 3 mm, the acceptable molding shrinkage rate should be 0.5% or less, and more than 0.8% may adversely affect the dimensional accuracy of the heat sink. The molding shrinkage should be as small as possible. If you choose a material with higher molding shrinkage, you will have to increase the wall thickness to make up for it.

4. Mechanical properties

The mechanical strength of a thermally conductive plastic radiator depends on several key indicators: Cantilever beam notched impact strength, tensile strength, bending strength, usually can be compared to different material indicators, the larger the index value, the better. The thermal conductive plastic with excellent mechanical properties can be added with a snap-fit ​​design in the heat sink structure, so that the interface of the PC cover or the lens and the heat sink is realized by the buckle, so as to avoid relying entirely on the adhesive for fixing. The problem of adhesive is that it requires curing time and prolonged delivery time, and the glue is easy to atomize at high temperature, which affects the light-emitting effect.

5. Flame retardant properties

There are two key points. First, whether it meets the UL94 V0 flame retardant rating will be more important for export to the US market. Second, whether it is halogen-free or flame retardant. Simply put, the flame retardant should not contain halogen, otherwise the environmental protection grade of the material. Will decline, it is more difficult to pass the European RoHS, REACH directive.

6. Insulation characteristics

One of the benefits of thermal plastics is insulation safety. If the molded heat sink can withstand high voltages above 3500V, it should be easy to pass the safety test. Matching such an insulated casing, the optional lamp board and power supply scheme can be more flexible, including: high-voltage linear lamp bead + high-voltage linear power supply, non-isolated power supply + medium-power lamp bead. Specific parameters can refer to the dielectric strength.

7. Thermal expansion coefficient

If a plastic-clad aluminum structure is used in the heat sink structure, the difference in expansion coefficient between the outer layer of the heat conductive plastic and the inner layer of aluminum alloy should be considered. The coefficient of thermal expansion of the aluminum alloy is 0.000024 mm/mm*k, and the expansion coefficient of the heat conductive plastic should be The same number of levels, otherwise it will not be able to synchronize thermal expansion and contraction, resulting in cracking of the radiator casing.

Third, the price

As a category of plastics, thermal plastics first follows the law of quantity. At the same time, it should be noted that the factors affecting the price are also closely related to the material density. The lower density material actually reduces the unit cost. In addition, the part of the rod in the injection molding can be crushed and re-injected and used, which actually has a certain impact on the price.

Fourth, value-added services

As a supplier of thermal conductive materials, whether it can provide customers with thermal simulation test services, will give customers a reference judgment on whether the custom radiators are qualified for heat dissipation. Therefore, after the mold opening is completed, it is found that the heat dissipation is unreasonable and the mold is modified, so that the risk of blind mold opening can be avoided.

Drum type Rice Cooker

Features

This type rice cooker is famous with drum type appearance, which is easy operation and easy clean.

There are two type of inner pot ,  one type called white pot which is without non-stick but cheaper price .another one called non-stick pot is polished with emery, Also there are two type non-stick with different price ,it`s depending on different demands to use.

And the inner pot cannot be burned on the stove, which will make the pot transfigured and bad contact with the heating plate. While cooking , the heating plate or the fuse is most likely to be burned for the bad contact of the inner pot and the heating plate, Besides, make sure to dry the pot before putting into the outer shell of the rice cooker ,or else the drops of water flowing on the heating plate, will make the heating plate rusted.

Applications

Many peoples are used drum type rice cooker for congee and soup, some of peoples are prefer to use this type rice cooker for steaming.

Drum Rice Cooker

Drum Rice Cooker,Drum Shape Rice Cooker,Electric Drum Rice Cooker,Multifunctional Drum Rice Cooker

Guangzhou Taipeng Electrical Appliances Technology CO., LTD. , https://www.taipengelectric.com