A historical branch of our production is specialized in the production of brazed tools and wear-resistant mechanical parts with hard metal coating.
Brazing consists of joining 2 components: the body and one or more hard metal or HSS plates.
This solution is adopted when, due to its dimensions, a solid carbide tool is too expensive.
Another field of use of brazed tools is that of complex profiles , which cannot be made using mechanically fastened tools due to problems of overall dimensions, tolerances or particular profiles.
The solution of the brazed tool therefore combines the advantage of the performance offered by hard metal, with the possibility of replacing any damaged coatings while preserving the body.
This technique is also widely used in the production of anti-wear parts, or mechanical components that undergo friction stresses. To last longer, these parts need a hard metal contact surface. Gaspari Utensili produces scrapers for cleaning belts for earth movement, sliding guides, bushings and many other wear-resistant articles upon request.
We mainly use two techniques for these tools: induction brazing and torch brazing.
Induction brazing uses the magnetic field generated by the passage of current on a twisted copper spiral. The tool is placed inside the spiral where the magnetic field heats it up melting the solder. We use this technique when making small tools, which require greater precision, or when we are making series of numerous tools. Modifying the power supplied by the current generator and the duration of the treatment, we have a greater control and repeatability of the brazing process.
Torch brazing is a welding process made with a torch and a mixture of propane and oxygen. The joint combustion of these two gases heats up the body, the hard metal plate and the solder until they melt and merge. This processing is made by our most expert hands, as it requires an excellent knowledge of the reactions of the materials to heating, the use of the right gas mixture and the choice of the most suitable solder for each type of tool.
In fact, each tool requires a customized brazing according to its specificity and the stresses to which it will be subjected when working.
Helix cutters, curly cutters and small hard metal coatings are made with an Italbras FB3 solder, in foil or rod melted at a temperature between 700 and 750 Celsius.
Parts that have larger hard metal faces, or that for technical needs have shallow support seats, require a stronger bond to the body. To ensure that the plate does not detach from the casing, a torch brazing with a silver-based trimetallic binder is used, with melting temperatures between 850 and 900 Celsius.
For the most delicate tools and where the joint area is very narrow, the risk of the brazing skipping is greater. An example of this are the anti-vibration tools with “V” coupling of the head on a hard metal body. In these cases the link between the stem and the head must be as strong as possible. Our expert staff solves this problem by using solder alloys with melting temperatures around 1000 – 1100 Celsius.
The production of a brazed tool requires numerous steps and measures that guarantee high performance standards.
We start with the realization of the body by turning and milling: in these phases the seats where the metal plates will be allocated are already made hard. A sandblasting with glass microspheres is then performed to eliminate any impurities, which would compromise the brazing result.
Then we prepare of the hard metal plates of the right length and sealing foil. Between the foil and the body, a deoxidizing paste is also added – an essential element to clean the weld from the oxidative effect generated by the heating of the body.
Once the brazing has been carried out, the tool must cool down inside a refractory brick powder, which gradually dissipates its heat. This step is essential to reduce the temperature of the product without a thermal shock, which would cause it to break. The tool is then sandblasted with glass microspheres, hot burnished and finally sharpened.