Sintex® - FAQ (Frequently Asked Questions)

Under denne FAQ sektion finder du spørgsmål og svar på de oftest stillede spørgsmål inden for vores produktområder.

Bemærk at FAQ sektionen er kun tilgængelig på engelsk.

Spørgsmålene kan sorteres ved at klikke på overskrifterne.

Currently showing 17 questions and answers:

Product	Question	Answer
MIM	Is it possible to give some design guidelines?	It is difficult to give precise limitations to design, but here are some rules of tumb: o Flow length below 100mm o Weight below 200 grams (preferable also below 100 grams) o Maximum thickness 6mm o Yearly production above 100.000 pieces
MIM	What is Metal Injection Moulding (MIM)?	MIM is a process combining the shaping advantages from injection molding, with the mechanical strengths of normal powder metallurgy (PM). The result is a process where it is possible to achieve geometries in a single step, which would otherwise demand either several steps, or not otherwise be possible. The process starts out with injection molding of the part, called a green part. The part is then debound, which can be done thermally, solvent or catalytic. After debinding the part is called a brown part, which is ready for sintering. After sintering it is possible to use a wide variety of processes to complete the part, for instance surface coatings, polishing etc.
MIM	What materials are available?	There is a wide range of materials available for MIM, the most common are: 316L, 17-4PH, 430L and FN02. But it is also possible to MIM Tool steel, Titanium parts and ceramic parts (called CIM for Ceramic Injection Molding).
MIM	Why use Metal Injection Moulding?	The process is very suitable for high production volume parts with a high complexity. There is some limitations on the size, parts above 100 grams are generally more difficult to manufacture than smaller parts. It is possible to achieve tolerances below 0.5% of the nominal.
Sintered Components	Can you do any tricks to reduce the porosities or increase the corrosion resistance.	PM components can be sintered with addition of a liquid forming agent. This increases the activity during sintering making the remaning pores spherical and closed to the surrounding. This leaves a surface without open pores making pitting initiation more difficult. Furthermore the spherical pores do not act as crack initiators which results in better mechanical properties - especially on the elongation and UTS.
Sintered Components	Can you make the same grades in stainless steel as we know from rolling and forging processes?	The grades produced in powder materials are almost identical to the grades known from other processes. On the chemical side you will often find larger levels of Si and lower levels of Mn in a PM-grade compared to other processes. This is due to the atomisation process and the compaction process where Si secures a low level of oxygen and Mn works as a deformation hardening agent reducing the powder compressibility and hence the green strength of the compacted parts.
Sintered Components	Can you reach the same corrosion resistance as known from stainless plates and rods?	The corrosion risks in stainless steel is pitting corrosion. As a PM component normally has around 15 volume percentage porosities you can look at the surface as pre-pitted making the pitting initiating attack easier. It is also known the the pore size can be critical for pitting initiation - the smaller pores the more critical. Therefore most components are designed with a relatively large amount of pores (density below 6,6 g/cm) in order to have better corrosion resistance. For components with high demands on corrosion resistance a PM processed component is often choosen in a more noble grade than needed in plate or rod material. In these grades Molybdenum plays a large role as Mo is known as a strong pitting resistance agent. The alloy STX2000 with 3,9%Mo is an example on this where the corrosion resistance is comparable to plate processed AISI 316L (2,3% Mo).
Sintered Components	Can you reach the same mechanical properties as known from stainless plates and rods?	Powder metallurgical process components contains porosities. As the pores acts as crack initiators the mechanical properties are typically lower than known from fully dens parts. Especially elongation is reduced and typically have values between 10 and 20% for stainless grades after sintering in pure hydrogen atmosphere. Furthermore the PM components are fully soft annealed after the sintering process, which can be seen on a low yield strength and low hardness. Both the yield strength and the hardness can be increased in coldforming post processing or by sintering in nitrogen containing atmosphere. The latter though reduces the toughness and the corrosion resistance.
Sintermetal	Why use PM?	Powder Metallurgy is a process route where a complex component can be produced in one single operation without any machining of the component. This makes the process economical interesting for many complex applications. Furthermore is the process highly reproducable and fits perfectly production of high volume parts.
SMC	Previous tests shows mechanical weak samples, we have problems with broken samples. Is this still a problem with materials today?	The first series of SMC was indeed weak - especially at higher temperatures, because the powder was bound by a plastic binder. Todays materials are cheramically bounded. The surface of the powder grains are oxided together with its neighbours. The mechanical strength is therefore much higher and it does not depend on temperature. A range of different powders and production methods exist. Giving the magnetic circuit designer freedom to fine tune the mechanical and magnetical properties.
SMC	We are interested in doing some SMC test samples. How will they compare to the final production samples?	Generally we highly recommend to make a powder compaction tool for the prototypes. With this tool the prototypes will be nearly 100% identical to the final production samples. Furthermore many samples can be made for a low cost per sample. Several different powder types and production methods can be tested. However the tool will cost some money, but 3 different tool qualities exist, with very different price levels. The choice of tool will depend on how many prototype samples you need, the delivery time, the tolerance demands and more. An alternative is to machine the prototypes from drilling, turning and milling, but a special prototyping material powder is used in this case. The magnetic and mechanical properties of the prototypes will thus not necesarily be equivalent to the final production samples. Contact our SMC expert for more information.
SMC	What are the limitations of designing whith smc. What are the finest/smallest fabricable structures? Are there any characteristic we should pay attention to while defining geometrical properties of smc based structures.	SMC particles are typically in the range 0,1mm, however during pressure the particles are deformed to some extend. We have a range of different powders with different characteristics, and the production process also heavily influence the mechanic characteristics. Mechanical details can be optimized a great deal in a run-in project. The samples are produced by axial compression, therefore there are limitations to the 3D structure, however the limits are much wider than traditional laminations. It is therefore very good to take these things into consideration from the very start. A very narrow collaboration in the concept phase is a great advantage. We are always available for comments and suggestions - typically we make a formal partnership with non disclosure agreement in advance of the cooperation.
Wear Resistant Coatings	How hot does the component get during the spraying process?	One of the major advantages of the HVOF spraying process is that the temperature of the components can be kept below 100°C. This means that there are no structural changes in the material of the component and thus no reduction of the corrosion resistance.
Wear Resistant Coatings	How thick a coating can we get?	We recommend a thickness of 0,15-0,2 mm. This is normally sufficient to obtain the best wear and corrosion properties. For a bearing, we would coat 0.3 mm in thickness and the grind off 0.15 mm afterwards to achieve the desired surface finish. On parts exposed to wear a coating of 0.2 mm is typically enough to stop the wear and tear, or minimizing it so as to achieve a significant life extension.
Wear Resistant Coatings	Is it possible to coat the inside of pipes and bushings?	The HVOF process is a spraying process with a very high particle velocity. This means that there is a distance from the spraying nozzle to the component of approx. 250 to 300 mm. However, inside coatings can be done at an angle of up to 45° - which means that the possible depth is equal to the diameter.

1 2 Næste