Diecasting die spraying need not be messy

With the growing complexity of large diecasting tools, die spraying can be messy, but the latest reciprocators and spray nozzles dor the job accurately and efficiently.

Although Frechs core business has always been building high pressure machines, it also makes it a matter of policy to offer everything necessary for the complete casting cells that are increasingly commonplace today, especially among high volume aluminium diecasters.

With the aluminium fraternity in mind - and the growing complexity of large diecasting tools - Frech has developed a completely new range of spray delivery tools and nozzles.

Spraying recessed areas inside cavities for large diecastings are a perpetual challenge because they are often inaccessible to the spray head and can therefore go unlubricated.

In many cases the answer could lie with Frechs SprayContour system, which can be built up from a kit of single - and multi-nozzle parts to deliver lubricant - where no other spray head has gone before.

The nozzles can be adapted to fit on most robots or reciprocating systems, improving their performance without the need for large investment.

Many die spray systems also have a minor but nonetheless irritating deficiency - dripping nozzles.

After the spray has been delivered and before the next cycle is initiated, any unused lubricant adjacent to the nozzle tips will inevitably drip out under gravity - often because the seals have deteriorated in the hot and dusty foundry environment.

This has no effect on the casting cycle per se; but it creates a mess that must be cleaned up at regular intervals if house-keeping standards are good, or is just left to accumulate.

Frech have addressed this problem with their 'Vapojet' spray head, which has a vacuum piston inside to take surplus lubricant away from the nozzle outlets and back into the manifold after every spray cycle.

Behind the array of nozzles at the die face is the spraying system itself of course, which governs where and when the lubricant is delivered and how much.

'Off the shelf industrial robots, usually with additional protection against the rigours of the foundry lifestyle, are often favoured for this duty.

But there is at least as good a case to be made for a system that is designed from the floor up to spray dies - and to spray them to perfection because it does nothing else.

Ever-shorter cycle times inevitably put the spray system under pressure - a problem that Frech responded to several years ago when it replaced the pneumatic systems it used to offer with its first electrically driven system under the name of Spraymotion.

Spraymotion 1 provided the single up-down action that in many cases is more than capable of the job - but a second option was soon added in the form of Spraymotion 2, which moves in two axes and can therefore follow closely the contours of the die cavity.

The 2-axis device was designed with cold chamber machine in mind, but is equally suitable for hot chamber duties.

It is designed and built as a modular device, with vertical and horizontal axes based on identical linear units enclosing the driving flanges, guides and bearings.

Robust geared belts transfer motion from highly dynamic servo-motors, and all the modules are constructed from aluminium to reduce weight and facilitate high operating speeds.

Enclosure of all moving parts protects against dirt, spraying dust and heat, complemented by a special coating on the external surfaces resistant to aggressive lubricants.

Built into the spraying arm are generously dimensioned channels capable of supplying sufficient air and liquid for even the most demanding casting jobs.

The control manifold has a pneumatic valve for each spraying and blowing circuit in the chosen spray head to prevent leakage during die changes.

The drive and the individual valves are all controlled over a common cable by means of a bus-module, and the manifold is easily accessible for maintenance and valve changes, which can be carried out in seconds.

Electronic controls are normally integrated into the machine control but other options are possible, allowing the sprayer to be installed on non-Frech machines.

Strokes and times can be set in up to 50 steps without any programming knowledge using simple graphic symbols, and the status of each action is displayed in real time, so that the operator can see exactly what is happening when the machine is running.

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