Austrian company Meltec chooses PDC to trial its brass vacuum dosing furnace on high pressure die-casting. This is one of the first of its kind trials in the world to be carried out.
Continuing with its strategic decision to move further up the value chain, with an emphasis on product delivery and quality, Pressure Die Castings (PDC) has now invested in a further two new high pressure die-casting machines. The new machines are a 630-ton aluminium pressure die-casting machine and a 400-ton brass die-casting machine. This new investment takes the number of aluminium, zinc and brass die-casting machines to 14 at the company, with seven new machines been installed over the last few years.
PDC have installed three new die-casting machines over the last year that have all been fitted with the Meltec dosing system. All three aluminium systems and the newly designed brass vacuum dosing unit that will be arriving shortly use a coreless induction furnace for holding purposes. Austrian company Meltec chose PDC to trial its brass vacuum dosing furnace on the new high pressure die-casting machine. This is one of the first of its kind trials in the world to be carried out
“Our drive is to replace all our pressure die-casting machines with modern new equipment, as soon as is financially possible. We are half way there and are looking to complete the exercise in the next few years,” commented outgoing Managing Director Mike Wolhuter.
Lessons from GIFA 2015
“While we take the efficiencies of our die-casting production machines seriously, we are also extremely cognisant of the fact that these machines are only as good as the metal supplied to them, which can ultimately have repercussions on the end product.”
“When we visited GIFA in 2015 we discovered an Austrian company Meltec, a manufacturer that is involved in melting and vacuum dosing furnaces for high-pressure die-casting. They had just launched a unique dosing system that fits onto melting and holding furnaces.”
“The system is unique in that it allows for filling of a container by sucking in the melt and the precise filling of the melt into the shot sleeve of the chamber of a die-casting machine. In the traditional variant a suitable amount of the liquid alloy is ladled out of a holding furnace and poured into the shot sleeve.”
Crucible furnaces are designed for melting and keeping die-casting aluminium alloys to the correct operating temperatures. High quality insulation is the reason for low power consumption, which results in low operational costs. The easy-to-move insulated cover provides good access to the melting bath and therefore simple maintenance is possible. Standardised graphite or silicon carbide crucibles enable an indirect melting of the aluminium alloys. Highly efficient and long-lasting heating elements, which are integrated in the furnace combustion, heat the furnace. Changing of heating is easily done. Activation of heating elements occurs via solid state relays, which keep the temperature of the melting bath free from overheating. Various forms of rotary degassing mechanisms can also be mounted on the furnace ensuring that molten metal will be degassed and the density index will be improved again
“The dosing system consists mainly of a vacuum ceramic container, an evacuation device to draw in the melt as well as a special closing mechanism at the suction point. The vacuum container is made of a ceramic material, which offers the benefit of being non-wettable, thermal shock resistant and strong. The mechanical movement occurs via a servo-controlled lifting or pivoting device.”
“The interesting aspect for us was that the system draws in the melt below bath level and fills the container by a sucking method. This minimises the oxide contamination while at the same time it degasses or removes the hydrogen from the melt. The transfer of the melt to the shot sleeve is therefore done without air admission, thus reducing oxide contamination, and there is very little drop in temperature of the melt.”
“An additional advantage is that of high dosing precision through integrated, exact quantity measurement. The cost situation of a foundry is largely influenced by the efficiency of the melting shop. As the non-ferrous metals that are processed in the melting shop are very expensive, metal loss is an important cost factor.”
“For aluminium, a metal loss of 1% of an annual melting output corresponds to a financial loss of many thousands of rands. Given a yield of 50%, this amount must be allocated and the lost metal means extra costs per kilogram of casting weight. This is a not to be neglected magnitude.”
The dosing system consists mainly of a vacuum ceramic container, an evacuation device to draw in the melt as well as a special closing mechanism at the suction point. Because the vacuum container is made of a ceramic material it offers the benefit of being non-wettable, thermal shock resistant and strong. The mechanical movement occurs via a servo-controlled lifting or pivoting device
“Also energy consumption may vary largely depending on the melting process used. Here not only the efficiency of the melting and holding furnace must be taken into account but all other factors effecting overall consumption must be considered, including all auxiliary energy sources. Likewise all maintenance-related and wear parts costs must be included in the cost considerations as well as the effort associated with the operation of the equipment. Considerable cost savings can be realised when mechanical devices are used e.g. robots, as opposed to manual operation.”
“It also goes without saying that you cannot keep ahead technologically if you do not visit exhibitions like GIFA. We are sending five people from our company this year and we expect to come back with a whole host of systems and methods that we can implement at PDC.”
Brass dosing system
“The three new die-casting machines that we have installed over the last year have all been fitted with the Meltec dosing system. Additionally, we have purchased the melting and holding furnaces from Meltec.”
The Meltec system draws in the melt below bath level and fills the container by a sucking method. This minimises the oxide contamination while at the same time it degasses or removes the hydrogen from the melt. The transfer of the melt to the shot sleeve is therefore done without air admission, thus reducing oxide contamination, and there is very little drop in temperature of the melt
“The system has worked very well with aluminium pressure die-casting in our foundry so the questions quickly arose about brass, another high turnover metal for us. After discussions with Meltec they have now chosen us as a trial situation to test the system for melting and transferring of brass.”
“We have invested in a 400-ton machine and the challenge for us now is to automate the whole process like we have done in other departments in our business. When you are processing up to 200 tons of metal a month and between 100 and 120 tons a month in our plastic extrusion and injection moulding departments you need to make use of all the equipment that can improve your efficiencies.”
Brass components manufactured by PDC
“With high quality equipment, automation and intelligent solutions, you can meet the global challenges as environmentalism, climate protection and energy efficiency increase while at the same time increasing your bottom line. Industry 4.0 is another concept that we are happily introducing to our environment because it can only be beneficial.”
After 25 years of service at PDC Mike Wolhuter will be retiring from his position as Managing Director. With effect 1 May 2019 Graham Smith will take over as the new Managing Director. Smith has worked for PDC for 16 years, initially as the Finance Director and more recently in his role as the Commercial and Operations Director.
Wolhuter’s knowledge and experience will not be lost to PDC as he will remain on as a Director on the PDC board and as part of the executive management team. Wolhuter will in future concentrate his efforts on his new role of implementing operational excellence within the whole company.
For further details contact Pressure Die Castings on TEL: 033 397 5500 or visit www.pdc.co.za