Sheet metal forming belongs to one of the most important technologies enabling the production durable but quite lightweight metal parts. The quality of the drawn parts depends on the deformed sheet metal, applied forming technology and process parameters, such as contact pressure, relative velocity, temperature or lubrication. The forming of steel (1.4021) parts using benign lubricant is analysed. The paper proposes replacing conventional mineral/synthetic lubricants with ones based on vegetable oils and boric acid. The effectiveness of the lubricants was assessed in laboratory strip drawing and cupping tests, and in production. An oil-based lubricant with an additive of boric acid is very effective in reducing frictional resistance and protecting the forming tools against galling.
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This paper presents the possibility of using the Spark Plasma Sintering (SPS) method to obtain WCCo composite materials. Such materials are used as cutting blades for machining wood-based materials. Two series of composites, different in grain size and cobalt content, were analyzed in the paper. The produced materials were characterized using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and tribological properties were determined. In addition, preliminary tests were carried out on the durability of the blades made of sintered WCCo composites while machining three-layer chipboard. The results of the microstructure analysis proved that the SPS method makes it possible to obtain solid composites. Phase analysis showed the occurrence of the following phases: WC, Co, and Co3W9C4. The lowest friction coefficient value was found in samples sintered using powder with an average primary particle size of 400 nm (ultrafine).
The paper analyses the forming of the surgical instrument handles made of Grade 2 titanium sheets. Sheet metal forming is a technology ensuring high strength and light weight of products. Replacing stainless steels with titanium further reduces instrument weight and additionally provides the required resistance to corrosive environments typical for surgeries. The low instrument weight is important to prevent fatigue of surgeons and allow them to maintain high operational accuracy during long term surgeries. The numerical analysis of the technological process was performed in order to adapt it to forming tool handles using titanium sheets instead of steel sheets. The numerical calculations were experimentally verified. It was found that, in the case of titanium handles, it is necessary to use a blank holder in the first forming operation to eliminate sheet wrinkling in the flange area. The shape and dimensional accuracy of the drawn part after trimming were high enough and the 4th forming operation became unnecessary. Moreover, the process modification included lubrication using rapeseed oil with the addition of boric acid, which effectively prevents the galling of titanium on the working surfaces of the steel tools and ensures a more uniform distribution of plastic strains in the drawn part.
Cemented carbides belong to one of the most important groups of tool materials, whose percentage among all other materials used for cutting tools has reached about 50% in the global industry. Powder metallurgy methods have been used to produce cemented carbides, of which spark plasma sintering (SPS) is considered highly prospective. This paper presents the results of preliminary research concerning the effect of the fraction of the binder phase and sintering temperature on the microstructure, density, hardness and resistance to brittle fracture of cemented carbides produced by spark plasma sintering. The test materials were WC powder with a purity of min. 99.5% and Co powder with a purity of min. 99.8%. The obtained mixtures (WC-3Co, WC-6Co and WC-9Co) were sintered using the SPS method at 1300°C, 1350°C and 1400°C. The heating rate was 400°C/min. The pressing load was 80 MPa. Density measurements were carried out using the Archimedes method in accordance with PN-EN ISO 3369:2010, while hardness measurements, using the Vickers' method, were performed in accordance with PN-EN 23878:1996. Resistance to brittle fracture was determined based on the measurement of the length of cracks formed on the corners of the indentation. The observations of the microstructure and analysis of chemical composition were carried out using the scanning electron microscope. The phase composition of the obtained materials was determined by means of X-ray diffractometry.
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