What factors affect the accuracy of Precision Casting dimensions
Precision Casting refers to the general term of a process, which refers to the use of sophisticated modeling methods to obtain accurate casting process, through Precision Casting can get a lot of castings, such as: hardware accessories, auto parts, motorcycle accessories and a variety of valves And so on, so it is now a very important industry in a process. So when doing Precision Casting, we need to pay attention to what factors may affect the accuracy of Precision Casting size?
First, the first is the casting structure is a very important influencing factors, the general casting wall thicker, the greater the shrinkage, on the contrary the smaller;
Second, the casting material will also affect the Precision Casting of the intensive, the general material in the higher carbon content, the smaller the line shrinkage, the opposite the greater the line shrinkage;
Third, the mold for the casting shrinkage also has a great impact, generally the temperature and pressure of wax and pressure holding time for the size of the impact are very large;
Fourth, the shell is also a very important factor, usually using zircon sand, zircon powder, on the shop sand, shop powder, etc., because their expansion coefficient is very small;
Fifth, the casting temperature is also a very important factor, the higher the temperature cast, the greater the shrinkage, so the need to control the casting temperature.
For people who often deal with the mechanical Precision Casting is certainly no stranger, we all think that the process is very simple, but easy to understand is not easy to have a lot of attention, the following will go with Xiaobian to see it.
1, Precision Casting Precision Casting wax mold surface of the various defects are fixed, flash, sub-line is clean.
2, repair the wax should be placed on the plate, keep the table and clean the site.
3, Precision Casting According to process requirements, the size, shape inspection, the use of check with a check.
4, to timely in the "logo card" on the logo.
5, Precision Casting repair mode as required, can not damage the wax mold.
Precision Casting has been very common, and many users in the casting process will be the case of bubbles. We will talk about the reasons and prevention methods.
Porosity is one of the most common Precision Casting defects, stomata refers to the Precision Casting individual position appears smooth hole defect. The stomata are usually found after machining. Yanzi Precision Casting technology staff with years of experience in the workshop, the Precision Casting of the reasons for the emergence of stomata and prevention methods are summarized as follows:
First, the reasons for the formation of: 1 because of the shell or shell-type material reasons, shell permeability is too bad, the cavity of the gas is difficult to discharge into the metal liquid to form pores; 2. Most cases of stomata is mainly because of Precision Casting shell roasting is not sufficient, pouring molten steel when the shell instantly produce a large number of gases can not be successfully discharged, and then into the metal liquid to form pores; 3. pouring into the molten steel in the air can not be discharged to cause casting porosity.
Second, the prevention method 1. Dewaxing wax material should be completely ruled out. 2. In the design of pouring system, to fully take into account the shell exhaust demand. 3. Shell firing temperature, time should be reasonable, the insulation time should be sufficient. 4. Properly reduce the distance between the pouring mouth and the pouring cup, the pouring speed should be uniform to ensure that the molten steel is filled with the cavity, as little as possible into the molten steel air, so that the cavity and the molten steel can be discharged smoothly. 5. In the case of Precision Casting conditions permit, in the structure of the complex castings set the highest hole.