Page 36 - trends in automation

I

n metalworking, greases and special

emulsions protect cutting tools

against wear. While this is good for

the machines, it leaves a residue on

the metal parts and must be removed

before further processing. Assembly pro-

cesses or surface treatments such as

galvanising or painting require clean parts.

Depending on the application, aqueous

cleaning solutions or solvents can be

used. Solvents are preferable to aqueous

cleaners for oily mass-produced parts for

the automotive industry as they are

quick, economical and resource-saving.

A new twin-chamber perchlorethylene-

based cleaning plant from Höckh Metall-

Reinigungsanlagen GmbH has raised the

bar with operation under full vacuum.

When integrated into the production cycle,

it increases part throughput significantly.

Up to ten crates filled with pressed and

stamped parts pass through the system

every hour in a three-shift operation.

State-of-the-art valve terminal technology

from Festo contributes to this excellent

performance.

Everything in one chamber

The capacity of the huge washing ma-

chine for metal parts is simply enormous.

Inaddition to rapidly cleaning large vol-

umes of metal parts in either a 65° or 98°

wash with liquid or vaporous perchlore-

thylene, the system also dries the parts

using a vacuum after they have been

washed. And all of this in less than 15

minutes per crate. Before that, the

pressed parts are transported in bulk.

Forklift trucks move the parts in crates

measuring approx. 900 x 800 x 850 mm

and with a total weight of between 500

and 600 kg. To select the right program,

the system operator simply scans the bar

code on the accompanying ticket. As soon

as he has left the loading area, automatic

feeding begins and the crate is trans

ported to the next free process chamber.

To achieve the required capacity of 10

batches per hour in a three-shift

operation, the process has been divided

between two chambers. The loading gan-

try then loads the rotating crate holder

and a Festo standard cylinder DNG with a

stroke of 180 cm closes the sliding door

of the process chamber vacuum-tight.

When it reaches the last few centimetres,

a clever toggle lever mechanism ensures

it is firmly closed.

10 batches per hour

Depending on the parts type, this is then

followed by an individual cleaning pro-

gramme, which can be made up of

various modules such as evacuation of

the process chamber to process vacuum,

pre-washing in the spray process, flood

cleaning (full bath) from tank 1, post-

washing in the spray process, flood

cleaning (full bath) from tank 2, vapour

degreasing with solvent vapour and

vacuum drying. A limit value encoder

monitors the drying process so that only

completely dry, solvent-free parts are

removed from the process chamber.

The cleaned parts then pass through a

cooling tunnel on the unloading roller

conveyor so that the crates can be

packed directly for shipment. To achieve

maximum flexibility, the system was

designed as three separate modules.

For cleaning there are two identical, com-

pletely independent cleaning modules

with process chamber, twin tank, distill

ation plant, pumps and filters. Because

of standalone operation, one module can

be switched off in the event of mainte-

nance or low capacity utilisation and the

system can continue to operate at half

capacity. Both cleaning modules are con-

nected to a central supply module, which

The door of the giant washing machine drum

is closed by a standard cylinder type

DNG with a stroke of 180 cm. When it reaches the last few centimetres, a clever toggle

lever mechanism ensures it is firmly closed (see photo on right).