30 JOT International Surface Technology 1.2014

Cleaning of Spheroidal Graphite Cast Iron

Cleaning and Phosphatising Robot Housing ComponentsReplacing aluminium with spheroidal graphite cast iron led to new challenges for parts cleaning

at a robot manufacturer. The problems were solved by a water-based system in which the robot

parts are not only cleaned but also iron phosphatised.

With a market share of around 50 percent, the company Kuka

Roboter GmbH in Augsburg, Germany, is the largest robot manufacturer in Eu-rope, and business is booming as there is an ever-growing demand for robots. Robots are increasingly being recog-nised as the most �exible machines for automation solutions, not only in the automotive industry but also in many other sectors.

For that reason, the German tech-nology leader is focusing on optimis-ing energy and lubricant consumption and the durability of its robots in or-der to minimise life cycle costs and in-crease pro�tability. Today, the technical availability of a Kuka robot is around 99.9 percent.

Main criterion – avoiding downtime“For the new Quantec series, we have replaced aluminium with spheroi-dal graphite cast iron, thus enabling us to reduce the weight of our robots by around 10 percent – while increas-ing their strength,” explained Franz Schwab production manager at Kuka. Spheroidal graphite iron can now be cast in much thinner shapes than ten years ago, so that the motion links and arms can be produced as single parts.

The change to the new material did, of course, pose some challenges with regard to corrosion protection and parts degreasing. “We had to invest in a new parts cleaning unit because our existing machines were too small or too

far away from the actual assembly line,” Franz Schwab pointed out.

As before, the company once again bought the new unit from the cleaning machine manufacturer Pero, follow-ing its very good experience with the cleaning systems supplied by this man-ufacturer. “�e main criterion in buy-ing equipment and machinery is po-tential downtime,” Schwab said, “and none of the units has ever needed a re-pair call-out.”

Integrated into the assembly cycleBased on this experience and the re-quirements of the new robot compo-nents, the decision was made to buy a Robomat 8U cleaning unit. �e unit is installed right at the starting point of the assembly line, and the cleaned housing parts are o�en still warm af-ter drying when they enter the assem-bly process. “�e cleaning unit is ful-ly integrated into our assembly cycle,” Schwab con�rmed. “�e cleaning jobs can thus be scheduled in line with the needs of our assembly process.”

Cleaning and phosphatising in a single process�e new cleaning unit is a sturdy stain-less steel single-chamber unit for aque-ous cleaning. It is of medium size with a parts cleaning chamber that is 2,100 mm wide, 1,040 mm deep and 960 mm high. �e processing chamber can be used for cleaning and rinsing as re-quired. Kuka currently uses a clean-ing agent that not only cleans the parts but also coats the surfaces with an iron phosphate film. The components are

Cleaning unit with the cleaning chamber lid closed

CLEANING AND PRE-TREATMENT J O T I N T E R N A T I O N A L S U R F A C E T E C H N O L O G Y

31JOT International Surface Technology 1.2014

Contact: Pero AG, Königsbrunn, Robert Huber, Tel. +49 8231 6011-0, info@pero.ag, www.pero.ag

rinsed with demineralised water taken from the second tank.

A spray arm with specially de-signed nozzles rotates by 340 degrees around the parts to be cleaned, apply-ing the cleaning and rinsing media, whereby Kuka is more concerned about ample wetting than high pressure. As the standard model comes with only a single rack for large workpieces, the unit supplied to Kuka was equipped with a special trolley. �is allows the rack to be moved out of the process-ing chamber so that heavy parts can be placed on it with a slewing crane.

High standards ful�lledAs the robot components are first transferred from the mechanical pro-duction department to the parts ware-house before they enter the assembly line, they also have the same incoming requirements: they are all treated with a preservation agent to prevent �ash rust, and this, of course, needs to be removed before the parts are coated. �is pro-duces an unusual situation: the clean-ing unit always performs the same sin-gle cleaning process, even though the control system allows up to ten di�er-ent washing programs to be run.

�is also applies to the parts that are cleaned for the sister company Ku-

ka-Systems. The machine is used for two thirds of its operating time for cleaning robot parts, and for one third for degreasing products from other di-visions.

�is makes the work easy for the operator, who must only ensure that parts with recesses – and almost all of the robot components have recesses – are placed on the rack in such a way that most of the cleaning and rinsing agent can drip o� freely. For that rea-son, the machine program is run for around ten minutes to provide ample time for drip-drying.

To dry the parts, the vapours are extracted from the processing cham-ber, thus allowing the surfaces to dry. If there is some liquid le� in the recess-es, the machine operator simply dries them manually with a compressed air gun.

“The quality of the paintwork of our robots fully meets our high stand-ards,” said Schwab, evaluating the suc-cessful application of the cleaning unit a�er one year.

The machine operator uses a slewing crane to transfer the parts – such as this motion link – to and from the cleaning unit

High qualitycleaning – fora reasonableprice!

Your customers demand highquality cleaning for their metalparts. Your highest priority iseconomy in the cleaning process.The perfect decision: a fully auto-matic Höckh cleaning systembased on solvents or water. In-terested in the right Höckh solu-tion for you? Visit us in the internetat www.hoeckh.com

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Tel.: +49 7082 41 09 31-10

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E-Mail: info@hoeckh.com

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