VACUUM CASTING Stage 5: Finishing

VACUUM CASTING Stage 5: Finishing

Stage 5: Finishing

During the #VacCasting process, we use certain components which help #resin to fill the mould perfectly. The main reason why this has to be done is because we must prevent potential problems from occurring; such as bubbles, bowing or sagging. These components include Feed, Sprue, Runners and Risers, which are only some of them. Besides, these components have also been cured in the mould alongside the part. So, following the demoulding process, these components need to be cleared in order to acquire the part. As PLG Global, we have #expert personnel to carry out this delicate process. Our personnel use advanced tools and #professional equipment so as to remove these integrants from the part. After the components are removed from the part smoothly, we have the exact copy of the part we have moulded.

Last but not least, some #PostProcessing is required. At this point, the replica of the part needs to be prepared according to our customer’s requirements. This means getting ready for putting the final touch to the part to give it a cosmetic look. Furthermore, the part may need these finishing touches in order to acquire a smoother surface quality, to obtain the right geometrics or for any other specification that our customer has demanded. Post-processing may also include polishing and/or painting the model. Our expert personnel are able to carry out all these processes according to what a certain part needs specifically.

Consequently, Vacuum Casting is a very cost-efficient method and it is highly preferred in rapid prototyping processes when it comes to producing challenging and delicate parts. It is widely used in industries such as consumer goods, electronics, automotive, aerospace and many more. Vacuum Casting allows you to produce parts with high precision, which is considered to be the number one benefit of it along with its cost-efficiency.

Urethane Casting

Urethane Casting

Stage 4 of Vacuum Casting process is called Urethane Casting. Urethane casting is both cost-efficient and highly adaptable while many different parts are manufactured repeatedly. It is also time-efficient, which minimises lead times as much as possible. Furthermore, it provides more freedom in terms of design, which is a plus for manufacturers and, of course, for clients. Another advantage of using urethane is that you can get high-quality surface finish, which is ideal for the production of low volume parts.

In this stage, we generally use high-performance #Polyurethane materials. Casting urethane is a delicate process and for this reason, each and every procedure must be followed carefully as stated in the recipes in order to refrain from making any mistakes. #ABS, #PMMA, #PP, #PA, #Glassfilled, and #PC are only some of the materials we can simulate in this process. The correct ratio must be used when these materials are mixed together. After #polyol and #isocyanate are mixed in the pot, the liquid #resin will be poured into the cavity of the #Siliconemould via hoses under a #vacuum environment and with the help of gravity. When the materials are mixed, a chemical reaction occurs which transforms them to solid form. It must be taken into consideration that it is sure to shrink as it becomes solid, though it is generally a relatively minor amount of shrinkage. Approximately 10-20 minutes later, #mould will be ready to be cured in the oven. Basically, we put the mould in a temperature controlled oven and wait for at least 2 hours. Cycle time depends on the material we use and the post-process requirements to fulfil our client`s needs. Now, we should demould the part and prepare the mould for the next shots and repeat Stage 4. This process can be repeated up to approximately 20 times.

Silicone Demoulding

Silicone Demoulding

Stage 3: Silicone Demoulding

We have prepared the master model. The amount of silicone which is necessary had already been calculated and poured into the frame earlier. As mentioned in the previous stage, it is essential to wait for a period of 12 to 24 hours in order for the silicone to get cured. It must be noted that this curing time depends on the kind of silicone that is being used. At this point, it is important that the silicone remains untouched. Following the necessary curing time, it is now time to demould the silicone.

Silicone demoulding is an extremely delicate process which must be carried out very carefully. To put it simply, demoulding the silicone means that the master model is detached from the frame manually. The first step of this process is to gently cut the mould into two parts. It must be noted here that the mould is not cut randomly. Rather, a predetermined line must be followed when it is being cut so that it is not damaged or deformed in any way. This must be handled as carefully as possible because it might be needed later on. One silicone mould can be used for approximately 20 to 30 times. For this reason, harming the master model means we must start over when we need to use it again, which means wasting precious time. As PLG Global, there are many different tricks we use in order to make this process easier to handle; such as releasing agents and using special tools. After the master model is extracted from its frame, it is now time to close the mould and to stamp it. Stamping it is essential for protection because it must be kept stable while casting. After silicone demoulding process is finished, Urethane Casting stage begins.

Vacuum Casting Stage: 2

Vacuum Casting Stage: 2

Stage 2: Pattern Post-Processing stage

Following data preparation stage and after the master model is 3D printed or machined, the post-processing process starts. Post-processing of the master model is an essential stage in vacuum casting process. The purpose of this stage is to create identical parts to the master model for which some detailing is required. Furthermore, the master model must be flawless in order to make sure that there are no flaws in the duplicated parts. To this end, the master model needs to be post-processed according to what the client is expecting it to look like. The surface quality of the master model will be duplicated identically in the shots that are going to be acquired from the silicone mould. At this point, there are some specifications which depend on what the client demands. For instance, if the model needs to be glossy then it is polished. If a matte finish is desired then it is sandblasted. As PLG Global, we use our expertise to handle the post-processing phase with the use of lots of tools. When the surfaces are ready, the next step starts which is positioning the part in the frame. Our mould designer chooses an orientation and places the master model in this frame accordingly. At this point, there are some specific features that need to be taken into consideration. Among these features are the density, viscosity, characteristics and flow direction of the resin. Before silicone casting starts, it needs to have some runners and sprues which should be determined. The last stage is wrapping the master model with robust metal plates and pouring the liquid silicone into it. It is essential for the silicone to wait for 12 to 24 hours to get cured. When the curing is finished, the silicone demoulding process begins.  

VACUUM CASTING

VACUUM CASTING

VACUUM CASTING

Vacuum Casting is a method used for Rapid Prototyping in Low Volume Manufacturing. Vacuum Casting, also referred to as Silicone Moulding, is the process of replicating a master model through the use of silicone moulds or polyurethanes. In other words, a part is modelled after its own shape in a silicone mould for pre-mass production purposes. It is an efficient method for low quantity production.

PLG Global has a team of able engineers who are experienced in processes including, but not limited to, Vacuum Casting. Basically, there are five steps in this process, all of which will be explained in detail. They are as follows: Data preparation, master model, silicone demoulding, urethane casting and finishing process.

Stage 1: Data Preparation

The first step of #VacCasting process is initiated in the software. You can export any #3D format type (#stp#iges#x_t etc.) on your #design platform and send it to us. First thing our engineers do is to translate it to #STL format. After that, it must be scaled in accordance with the shrinkage specs of the #silicone and #polyurethane that is going to be used. At this point, our engineers should anticipate how the part is going to react in the mould in the most correct way. This is the part that requires the most efficiency in this stage. The last step of data preparation is sending it to our #digitalmanufacturing machines. It can be a #3Dprinter#CNC or any other proper technique. For our master models, we generally use #VAT technologies; such as #SLA#PolyJet#DLP, #LSPc and so on… Then, while the part is being printed, we calculate the amount of the polyurethane (#PU) resin or silicone that is going to be spent in the next stage which is the post-processing of the printed / machined master model.