Many customers lack the understanding of the production cycle of silica sol castings. They wonder: “Why it takes such a long time? I want to receive products quickly after placing an order.” In such a fierce market competition, occupying market share is a race against time. As a manufacturer, we understand this kind of thought very well. However, in order to produce excellent quality products, we must ensure sufficient time.
In the following passages, I would like to analyze the process flow of silica sol castings and the time required for each process in general.
Silica sol castings mainly have four major processes: wax making, shell making, casting, and post-processing. After these four major processes are completed, the casting blank can be produced to meet the basic needs of customers. The subsequent processing can be carried out according to customer requirements such as surface treatment. What’s more, these four major processes can be divided into more than 20 sub-processes, and that’s why silica sol dewaxing casting process is so time consuming.
Wax making is not just a wax model made according to the mold. We need to make matching wax sticks according to different wax models. After the wax model is completed, a manual full inspection is required to trim and repair the produced wax model. The fully qualified wax model is then bonded with the wax rod to form the tree. The time required for the entire wax making process is generally about 3 days.
The picture below shows how a wax mold is made according to the mold.
The picture below shows how to trim the waste edge of the wax mold produced.
The picture below shows the blow-out and appearance inspection of the finished wax mold.
The picture below shows how to weld the wax mold to the wax stick.
Shell making process is the most important process in the production of silica sol. About 40% of the casting quality problems are due to the imperfect completion of this process. Silica sol castings are different from water glass castings. Generally, silica sol castings require 6-7 shell layers. The gelation process of silica sol mainly depends on the dehydration and drying of silica sol, and the final hardening of silica sol generally takes more than 12 hours. Besides, it takes longer for some parts that are difficult to dry such as deep holes. At the same time, because the silica sol casting mold shell needs to be manufactured in layers, each layer needs to be fully dried to ensure that the lower layer of the shell will not cause remelting and falling off when the coating is dipped. What’s more, the moisture will penetrate into the dried shell when the coating itself is dipped Inside, resulting in a long overall drying cycle. Finally, we need to put the finished mold shell into the dewaxing furnace for dewaxing treatment. Therefore, the entire process of shell making generally takes 7-10 days to complete.
The following two pictures show how the first layer of shell is made. The same process needs to be done for 6-7 times, and each time drying needs more than 12 hours.
The picture below shows how the operator is recording the parameters and time of the third layer of shell making.
The picture below is a drying workshop with constant temperature and humidity during the shell making process.
Casting is a job that that highly depends on technology. There are many casting processes, and each process affects the quality of castings to a greater or lesser extent, so we need to be careful and pay attention to them. Pouring mainly includes mold shell roasting, raw material smelting and pouring. What needs attention is the temperature and time of roasting, smelting and pouring, as well as the chemical composition spectrum analysis and chemical composition ratio in front of the furnace. Smelting is a very important part in the casting process. It has strict control over the material, melting temperature, melting time and the amount of deoxidizer added. It is also necessary for the smelting masters to have professional technical knowledge and rich work experience in order to smelt qualified molten steel. The entire casting process takes about 2-3 days.
Because of casting problems, various defects of products occur very frequently. Fortunately, Besser Casting has more than 20 years of casting experience and a large number of technical talents, which can effectively avoid problems and save production time.
The picture below shows the roasting process of the product.
The picture below is the casting process of the product.
The picture below is the cooling of the product after casting.
This is the beauty process before the product leaves the factory. There are many post-processing procedures, so a lot of people are needed. After the casting is cooled, it can be transferred to the vibration shell process. In order to further remove the residual shell on the surface of the precision casting, hang shot blasting is required before cutting. It is the method of spraying cast iron sand shots in the hanging shot blasting machine to remove the remaining shells on the entire casting tree. It is not allowed to cut the casting body during cutting, but it is also not allowed to leave too long an inner gate, which is about 1-2mm, so it is necessary to polish the gate. After the above process is completed, shot blasting is performed again, and part of the qualified products can be put into the warehouse for shipment after inspection by the inspector. However, a small part of the castings still have quality problems such as defects and fleshy, which requires the subsequent staff to repair welding and polishing, until all products are inspected by the inspectors before they can be put into the warehouse. It takes about 7-10 days.
The picture below shows the shell vibration process after the casting has been cooled.
The picture below shows the shot blasting process after the shell is shaken and before the gate is cut.
The picture below shows the cutting process.
The picture below shows the gate polishing process.
The picture below shows the shot blasting process after the gate is polished.
The picture below shows the inspection process of the product, which needs to be classified into meaty, lack of meat and other defects.
The picture below shows that some products need to be repaired because of their welding defects after inspection.
The picture below shows some defects that need to be polished after inspection.
The picture below shows that some products need to be knocked out after inspection.
The picture below shows the second full inspection of the appearance of the reworked product.
The picture below shows the shaping process of castings.
The picture below shows the hardness test of the product after heat treatment.
The picture below shows the mechanical performance test of the furnace test bar.
Silica sol dewaxing casting products take about 19-26 days to complete only the process on the production line, and more than 20 processes are required to produce products that are satisfactory to customers. We need to control and overcome so many problems and risks in the production process. Once a skilled worker injury occurs in a certain process, or the number of rework processes of a certain product increases sharply, our bottleneck process will form and cause low efficiency to the entire production line. Under normal circumstances, we will do 10%-15% of the order quantity in extra in the first process to prevent scrap or batch rework in the next 20 processes.
My original intention of writing this article is not to persuade our customers to be infinitely tolerant of our delivery date. Rather, I hope that through this article, our customers will agree to place orders as early as possible, leaving us plenty of time for order placement and production. The pursuit of shortening the delivery time has always been the direction of Besser Casting.
Of course, we are very grateful to our regular patrons for their continued support. For those patrons who have been doing business with us for more than ten years, they are more friends to us than customers.
We will not let this sense of security hinder our progress. Instead, we will unremittingly improve the quality of service to new and old customers, which is our ultimate goal as Besser Casting team.