With the continuous development of the economy and industry, people’s demands and requirements for products have gradually become higher and higher. At the same time, the ability of precision lost-wax casting technology to solve the complex structure of products has been recognized by the industry. Ordinary precision dewaxing casting process includes water glass process, silica sol process, compound process, etc. Among them, the silica sol process has achieved the highest casting quality and the lowest processing speed among many processes. It is also widely used for casting products such as small and medium-sized parts and ultra-small parts due to its high density.
Half of the process of silica sol dewaxing casting is related to wax patterns. Since the precision tolerance of CT6 silica sol dewaxing casting can be guaranteed, this means that the smallest tolerance precision is only plus or minus 20 filaments. Therefore, the requirements for the shrinkage rate of the wax patterns used in the process are very high. In all steps, the shrinkage of the wax pattern is closely related to the size of the subsequent product. As a result, the quality of the wax pattern is one of the important factors that directly affect the quality of the casting. The size of the wax pattern directly determines the size of the finished product after casting the mold shell in the later stage. Therefore, in the silica sol dewaxing casting process, green medium-temperature wax with high stability is usually used. Water glass and compound lost wax casting processes usually use white low-temperature wax, which is more advantageous in terms of cost.
In this article, we will introduce the stability control method of medium-temperature wax in detail.
After being used at high temperatures for a long time, some components of the medium-temperature wax material will be oxidized and deteriorated. In addition, metal ions will also enter the wax material, making the wax worse and containing more impurities. To make matters worse, wax shrinks very differently than new wax. Since shrinkage is different from solid impurities, it is difficult to completely resolve it only by sedimentation, dehydration, or filtration. The factory must regularly remove part of the old wax and replenish new materials to ensure the overall stability of the wax’s performance. When the shrinkage fluctuates greatly, it is necessary to separate a part of the wax and increase the input ratio of new wax to neutralize the shrinkage of the wax. At present, there are professional medium-temperature wax manufacturers that can regenerate waste wax. Due to the special impurity removal process, the ash content in the regenerated wax can be lower than that in the original new wax, and other properties can be adjusted at will. Companies with general capabilities will also equip their factories with a systematic medium-temperature wax degradation and dehydration device, which will greatly stabilize the shrinkage rate of medium-temperature wax. It can be seen that different factories have different processing methods and different wax shrinkage rates. Therefore, sometimes to save costs, when customers change suppliers, they directly send the original supplier’s molds to us for use. Samples must be tested to ensure that the dimensions of the final product meet the drawings. In some cases, it was necessary to modify the dimensions of certain molds due to differences in wax shrinkage.
To strictly and stably control the shrinkage rate of the medium-temperature wax, the quality of the medium-temperature wax is very important. We need to control the wax material from the source, reduce the impurity content, pay attention to the wax handling and use process, and not allow high-temperature treatment to prolong the service life of the wax material. To control the shrinkage rate of medium-temperature wax in real-time, the factory will customize a mold dedicated to the size measurement of wax parts and set up a designated wax injection machine. In addition, professionals are assigned to operate the machine strictly according to the specified parameter settings. At the same time, the commissioner will measure the wax pattern and record the data every day, and compare the most recent data to confirm whether any adjustments to the current operation are necessary.
In addition to the above-mentioned control and supervision, in daily production, to realize the control of the size of the finished wax film, the setting parameters of the wax injection machine must be set strictly according to the values given by the technician. Because the medium-temperature wax has a higher temperature during the injection process, it will shrink slightly after cooling and molding, which means that its size will also change slightly. If the values of temperature, pressure, and time do not match during wax injection, it will directly lead to the loss of wax dimensional control.
We are not only committed to providing customers with compelling casting solutions but also committed to providing customers with stable batch product quality. The latter is the object of our strict process controls, which include the wax shrinkage discussed in this article.
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