A brief discussion on RHCM technology

RHCM refers to Rapid Heat Cycle Molding. High gloss is its typical feature, but not the whole. We have made the high gloss mold for several years, mainly using in the external decorative parts of household appliances, such as the front panel, decorative pieces, etc.. However, we always meet the same issues such as the weld marks, sink marks and other molding problems, which greatly affects the structural strength and appreciation of the product.

--The traditional injection molding process
On the one hand, setting the low mold temperature can reduce warping and shrinkage, shorten the molding cycle, but it is easy to produce weld marks and bank marks, low gloss, rough surface and other poor appearance. On the other hand, setting the high mold temperature can improve the appearance quality of the product surface, but it is easy to produce warping, sink marks, poor dimension, etc., resulting in the longer molding cycle and the higher cost.
--RHCM technology
RHCM technology uses a special quick-cooling and quick-heating temperature control equipment, which can solve the above two problems at the same time. It uses steam generated by a steam furnace or high-temperature water and cooling water, to control the mold temperature within a molding cycle by rapid exchange, so that the advantages of the above two traditional methods can be played.
--Details
First of all, before the injection, inject high temperature water or steam into the mold, so that the mold temperature exceeds viscous flow temperature of the resin thermal deformation. And then, inject molten resin to make the material temperature at the front-end feeder keep the viscous flow state, resulting in molding products with good surface quality.
After the molten resin injection is completed, the cooling process begins. Using cooling water makes the mold temperature quickly drop to the temperature of resin thermal deformation  below. In this way, the curing speed of the resin can be accelerated to shorten the molding cycle and solve the warping, dent and other issues.
--Advantages
RHCM technology can remove the welding lines, wave marks, silver marks and sink marks on product surfaces, which makes the product surface finish reach the mirror level and achieve the effect without marks. The product does not need the subsequent process of spraying, which effectively reduces the cost and shorten the delivery time. In addition, RHCM technology can also solve the floating fiber phenomenon caused by fiber addition products, so as to make the product quality more perfect. In thin-wall molding, the injection of molten resin at a high temperature helps to improve the fluidity in injection molding, reduce injection pressure, avoid short shot and air trapping. Eventually, product quality and strength can be improved. Through the rapid cooling after molding, it can also reduce the shrinkage stress and make the demoulding easy. At the same time, it can also reduce the injection cycle of thick wall molding by about 60-70%.

--Outside panel of DVD/DMR/BD/BR/PDVD and other audiovisual player
--LCD of TV/computer/automobile, air conditioner, and other home appliances
--Optical instruments
--Automotive interior parts and lights
--Communications
--Medical

The full closed-loop system controls the detection of input and output temperature. The temperature sensor is designed inside the mold and the actual temperature of the mold is fed back to PLC. The digital color image is displayed to ensure that the output is accurate and stable. Steam or high temperature water, cold water, and mold temperature display, is signal interlock with injection molding machine by the time and action.

The key points of RHCM technology are the mold, material, mold temperature control machine. Secondly, the injection molding machine has the higher reaction sensitivity, the better stability and quick feed back of the signal in real time.
--Mold match
The mold design should consider high temperature resistance, waterway applicability, installation matching degree and other factors. Let us share with you the injection process of RHCM. Firstly, make a balanced heating channel on the mold by using the high temperature water or steam. Secondly, when ejection, high temperature circulating water is injected to raise the mold temperature to a set value, and then inject plastic into the mold cavity. Thirdly, when the injection molding machine finishes the holding pressure and starts to cool, the hot water is to be recovered and cold water is to be injected. In this situation, the mold temperature will drop to a set value soon and then the cold water to be recovered. Because it is the molding process of sudden cooling and sudden heating, the mold needs withstand rapid thermal shock. Therefore, it is very important to select the mold steel with good thermal fatigue strength.
--Mold temperature controller
It can quickly produce enough high temperature water or steam, and interlock with the signal of the injection molding machine to achieve closed-loop control.

--Mold cost: The cost of the small and simple mold will be increased slightly by about 15-30% due to use matching waterway design and high temperature resistant parts, however, the large mold should be calculated at actual cost.

--The equipment scheme: Composed of high-speed heating, device, rapid cooling device, control device and injection molding machine.