Release agent, also known as release agent, as the name implies, is used in the alloy casting and plastic molding to lubricate the mold so that the workpiece and mold from the use of a solvent. However, its performance is affected by the temperature of the mold. Therefore, it is necessary to select a suitable mold temperature range of mold release agent during operation, and at this point, there often exists a blind spot in the die-casting operator.
However, in the production of die-casting, the release agent is an important means of mold cooling in the large sense (in the die-casting production process workers often hear: "the temperature is higher, more spray water," more spray point Water ", etc. Many companies are using water-based release agent, spraying compressed air with a release agent sprayed on the surface of the mold cavity at the same time, due to the high temperature die mold indirectly heating, resulting in The moisture in the release agent is evaporated, but because of the uneven temperature of the surface of the mold cavity, the release agent is heated to different degrees by the mold (the residual amount of water is different and the effect of gasification is different). The degree of mold is different from the mold release agent cooling, mold release mold surface formed liquid mold release, lubricating the thickness of the coating is also different.
In the mold hot zone, the mold release lubricant and the moisture in it are more affected by the mold temperature, resulting in a gradient of volatilization. If the temperature difference between the hot zone of the mold cavity and the surrounding cold zone is large, the tension gradient formed on the surface of the mold cavity is larger, and then the mold release agent is disturbed by the outside world (temperature, concentration, etc.) Of the liquid film thinning, it will die cavity surface tension (this process is like liquid metal in the mold cavity cooling and solidification process), the liquid film thin (mold high temperature area) to the liquid film relative to Thick place (mold low temperature area). If you increase the spray volume, will make the mold cavity hot zone completely covered by the release agent, the result is the accumulation of too much mold release agent and moisture in the low temperature region of the mold cavity, resulting in the formation of pores, Cold septum or stains and so on. (So many experienced die-casting operators will choose different ways to "spot spray" to overcome this phenomenon). On the contrary, the spray volume decreased, the hot area of the mold cavity was not covered by the liquid film of the release agent, which affected the lubrication and de-bonding effect. This shows the temperature of the mold release agent how much effect. Maintaining a balance of mold temperatures and a general agreement on how important mold release agents play is important.
In fact, in the die-casting production process, such as aluminum alloy die-casting: due to spraying time, take soup time forced cooling, injection delay and other factors, and the mold cavity surface temperature before injection can reach 250 degrees, because the heat Transmission speed and mold temperature control system under the effect of pre-filling mold temperature will exist 50--100 degrees of error, that is 250--300 degrees. Generally the best mold temperature should be about 40% of the casting temperature, so choose the release agent (BLD-3810, we used before) the optimum temperature range is 250 - 300 degrees. Only to ensure that the mold temperature control within the temperature difference, the demoulding effect is better, the product is bright, the mold does not coke, not sticking mold, but also relatively improve the service life of the mold and the use of release agent, direct Save costs!
Once into a good company, die-casting mold temperature is generally high 280 - 350 degrees, or even higher. The same use of BLD-3810 release agent (all others to use the effect is better), but we use them together is the effect is very poor, workers, technicians, foreman grumble! Do not mention that bitter ah! Dead people, the product pull-die, sticky mold surface, mold surface carbon. Obviously this release agent can not adapt to such a high mold temperature, the so-called fit is the best to use it! No way only to replace the company's another release agent BLD-3810, the effect is obviously better , I feel above the cavity has a layer of very shiny oil-like stuff! Non-stick mold, and very few die, die cavity surface almost no carbon deposition. For the mold temperature control according to the method of spraying different effects are completely different, the internal mold cooling effect accounted for 50% -80%, if you choose to spray machine automatically sprayed about 40% take away more than the heat, manual spraying about take away 15% of the heat. There are some differences in the operating habits of a certain discrepancy, 85% of the heat depends on the internal mold cooling and convection. Different die-casting machine, die-casting mold of different structures, different mold temperature control mode, resulting in different mold temperature. The temperature difference can reach 130 degrees, so even if the same machine, the new and old mold due to the different mold conditions and mold temperature, the choice of die-casting process and the effect of release agent requirements are also different.
A lot of mold release agent is poor, the performance of mold release agent problems appear more in the mold heated or the strongest metal flow position. When the surface of the mold cavity is not covered or covered by the mold release agent liquid film, many troubles such as poor mold releasing effect are easily appeared, so only by ensuring that the surface temperature of the mold cavity is equilibrated to make the mold release agent in the cavity Surface gets better and more uniform deposition. However, not all mold release agents can form a good coating on the surface of the mold cavity. Therefore, the ability of the mold release agent to wet and spread on the mold cavity surface depends on the mold temperature and the composition of the mold release agent itself. Water-based mold release agent will generally have a maximum temperature range, that is to say in this range of mold temperature, the mold cavity surface wetting and auxiliary exhibition is the strongest. When the temperature reaches a certain height, beyond the mold release agent temperature tolerance, its mold cavity surface wetting and auxiliary exhibition is the worst. Because of the composition and effect of the release agent itself produces a matrix change. For example, when you just remove the product from the mold, when the temperature is high, a drop of cold water on the casting surface, the water droplets floating on the casting surface for irregular sliding. Mold release agent to withstand the maximum temperature depends on its composition, spray pressure, angle, spray volume, and other factors, the pressure and the concentration of the release agent has little effect on the gas pressure, spray angle, and intensity can also affect Wetting and auxiliary performance, but the composition of the release agent wetting and auxiliary exhibition the greatest impact on capacity.
Mold surface temperature is too high or too low will affect the mold release agent to reduce the adsorption effect.
A, too low: when the temperature is lower than 150 degrees, the spraying process makes the mold temperature dropped below the water vaporization point, the paint is just a punch from the surface of the cavity, can not be deposited in the cavity surface, excessive water and paint Accumulation in the cavity will produce diffuse porosity of the casting.
B, too high: When the temperature is higher than 398 degrees, when spraying, the paint will be scattered on the surface of the cavity of the vapor, washed away. Because the temperature did not drop to the wetting temperature, only to reach this temperature, the fog coating will contact with the cavity surface will form a release liquid film.
For a relatively constant mold temperature, the factors that affect the formation of the film include the impact of droplets, wetting the mold surface, spreading to form a continuous film, preventing subsequent spraying and the like. In addition there are many uncertainties affecting the formation of the membrane. Including the speed of spraying, spraying intensity, spray angle has been formed and so on. The primary purpose of mold release agents is to form the most effective coating in the cavity and secondly to achieve the most efficient mold cooling and minimum residue.
Die casting supplies market a new release agent release, the new release agent to solve some of the old problems, with the continuous innovation of the peripheral technology of die-casting, mold temperature control and monitoring we pay more attention to the use of tools and Equipment is more advanced, so that we use the release agent more convenient, scientific and reasonable.
when using alkaline fillers, such as calcium carbonate, acid mold release agent will react with it, causing the mixture viscosity, but will not affect the stripping effect
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