Sintering and debinding of ceramic and metal parts

Sintering and debinding of ceramic and metal parts

A sintering furnace for 3D printing is required for the sintering and debinding of ceramic and metal parts just as it is for traditional processes like Ceramic Injection Moulding.

3D printing can now be used to manufacture complex shapes. Previously it has not possible to produce such shapes using conventional techniques. If a CAD file is available it is no longer necessary to have tooling made. So significant time and money savings can be made on many projects. But ceramic 3D parts require sintering and debinding as do traditional process.

YES we can!! – For those customers who do not have this type of equipment, and do not wish to make the initial investment involved in acquiring them, we can support you in having ceramic or metal parts sintered. Let us know about your project here.

As with many traditional ceramic forming processes, and for that matter; 3D printing of materials like metal, as used on systems like Markforged Metal X, will require the use of a carrier. The ceramic and metal materials, as supplied by 3D Matters in the UK, also require a carrier.

A sintering furnace for 3D printing is used to obtain the required density (up to 99.5%) and to achieve the desired mechanical properties it is necessary to extract the carrier material after printing. Debinding with a chemical bath or or thermal debinding in a furnace to apply heat, is the process to rid the part of this carrier. The time taken to do this depends on the geometry but can take up to 24-36 hours. The part will need to be sintered to make a fully dense part. It then has the fantastic material properties we all know and want from ceramic and metal.

Sintering and debinding of ceramic and metal parts

Debind and Sintering Process

As an example, we conducted the following high temperature cycles on parts;

A furnace containing alumina parts are heated to 225°C with a heating rate of 2°C/min. Then a second phase; where parts are heated to 550°C. A heating rate of 1°C/min and maintained for 2 h. Thirdly, the parts are heated to 1,300°C. A heating rate of 6°C/min and maintained for H minutes (H = 40, 65, 90, 120, 150, 180 min).

Finally, parts are cooled to 600°C with a heating rate of 6°C/min and subsequently cooled in a furnace. The samples were denoted as S(H), and H = 40, 65, 90, 120, 150, 180 min.

Thermal debinding and sintering temperatures and cycles will vary depending on the ceramic or metal material being used.

With most oxide ceramics it is not necessary to use gases like hydrogen and nitrogen, although there are occasional reasons to do so. Processing nitrides, carbides and metals will require sintering under gas to achieve fully dense parts.

Cycles Times

Ramp ups and hold times are proven to influence the intergranular bonding of ceramic/metal particles within a geometry. It is more of a factor in 3D printing where parts are built layer by layer. These factors need to be managed. For example, it is known that pores decrease in size by approx. 25% with a doubling of a hold time from 30 mins to 60 mins so directly effecting the parts’ porosity.

The cycle time and temperatures can be run as defaults as supplied. They can also be altered to optimise the process for certain applications. Experimenting with the parameters gives different outcome as is a key feature of our technology. Especially this is the case in the education and R&D sectors. This is in contrast to most systems in the industry. For example, the sintering process on the Metal X is a closed system. Here, the focus it to make it easier for users to obtain parts in a controlled process with very limited alteration to the parameters.

During debinding and sintering will my part change in size?

The removal of the carrier is necessary to obtain dense ceramic and/or metal parts. Therefore , it is inevitable that the loss of the carrier will occur during the debind and sintering process. It is typical to expect a shrinkage of approximately 20% but is dependant on the material and cycle profiles. 3D Matters provides training so that accurately printed parts can be repeatably achieved.

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