Vacuum Debind And Sinter For Ultimate Component Purity
During the debinding process, all binders must be completely removed from components, and contaminants that could foul the furnace or pumping system must be evacuated. These contaminants will affect furnace performance and quality during the sintering process. The design of the VFS Model VDS (Vacuum Debind/Sinter) solves this problem by utilizing not one, but two vacuum pumping lines.
One vacuum pumping line removes binders and carries them out through the bottom of the furnace. The pumping line incorporates an optically dense, water cooled baffle trap with a removable insert for ease of maintenance. The design utilizes an additional water cooled trap also with removable (replaceable) filter inserts in front of the vacuum booster to collect residual binder material.
If high vacuum is required, a second vacuum pumping line is connected to the high vacuum diffusion pump's main poppet valve. After the binder removal portion of the cycle, the high vacuum pump is available for the sintering process. The sintering process can also be run with process gas if required.
Sintering is a process required for many different parts and applications, including powder metal parts and metal injected molding (MIM) components, 3-D metal printing components of various types, and beading applications including abrasives. The parts are then heated to the binding agent's vaporization temperature. The temperature is held at this level until all outgassing of the binding agent is complete. Debinding segment control is provided through the application of a suitable partial gas pressure that is above the vapor pressure temperature of the other elements in the alloy base material. The partial pressure is normally between 1 and 10 Torr.
The temperature is then increased up to the sintering temperature of the base alloy and maintained to ensure that solid state diffusion of the part occurs. The furnace and parts are then cooled. Depending upon the application of component metallurgical requirements, cooling rates can be controlled to meet hardness and material density requirements. The chart show above is an example of a typical debinding/sintering cycle, which includes the use of a partial pressure gas during the debinding phase, and rapid gas quenching to meet specific material hardness requirements.
Vacuum debinding and sintering in one process cycle not only saves heat treaters time and money, but also results in superior and more consistent part quality. The main benefits of the VFS vacuum debinding and sintering furnace system are:
Sintering Part Applications
- Quicker processing turnaround. This one-cycle technology permits virtually unlimited design flexibility.
- Higher process quality (vacuum versus atmospheric).
- Minimization of contaminants to the furnace and components.
- Production of clean and bright components – a requirement of the medical industry.
- Furnace reliability and component repeatability. Maintenance "friendly" for cleaning and contaminant removal.
Several industries rely on sintered parts and components including:
- Medical parts, particularly implants
- Automotive – Power transmissions, gears & sprockets, camshafts, diesel particulate filter and valve seats
- Tools – Screwdrivers, drills, cutting/grinding tools