One tap for a million bottles

Krones AG is headquartered in Neutraubling, Germany, where it designs, develops and manufactures machines and complete systems for process industries, bottling plants and packaging plants.

Around the world, millions of bottles, cans and moulded containers are filled using equipment supplied by the company. The group includes not only Krones but also 90 sales and service subsidiaries at home and abroad.

The Nittenau location is the Krones centre for production and assembly for filling, labelling, plastic and process technology. This is a customised machine building operation, meaning each machine is either specially designed to customer order or manufactured as part of a small series.

“Around 90% of our products are exported,” says Stefan Wagner, responsible for tool management at Krones Nittenau. “Despite this we develop and produce our machines here in Germany. That’s because we have a globally competitive position which we have gained by rigorous application of technology and automation. Our range of modern machine tools puts us in the position to deliver on time despite tight delivery deadlines.”

In order to maintain its technological edge, Krones regularly engages in research and development and invests in evaluating new production processes and tools.

“The introduction of new tools is costly because it means we have to change the data in all our IT systems, databases and machine control programs,” explains Mr Wagner. “Therefore before we commit to a change we perform intensive tests on each tool.”

When the Hoffmann Group brought out its new Garant Master Tap general-purpose high-performance tap‚ Krones immediately set-up a test program. The tap is designed to perform with high process reliability in a range of different materials such as steel, stainless steel, aluminium, brass and cast iron, therefore replacing several other taps on a machine.

The tap has new cutting edge geometry, optimised chip flutes and a special configuration of tooth rear face geometry which breaks the swarf off at the root and evacuates it with high process reliability. The tap achieves a long working life even when tapping high-tensile steel, because its cutting edges are honed and protected against breakage. Tool material of high-quality HSS-E-PM and an ultra-smooth AlTiX high-performance coating prevent material adhesions and galling and permit high cutting speeds, even in wrought aluminium alloys.

“When the new super tap was announced our ears pricked up because during production of steel rings for carousel systems we continually have problems with twisted swarf, and during production of small components we constantly have to change taps,” explains Mr Wagner.

Stainless steel filler rings up to 7m diameter are made at the Nittenau works. Each ring requires hundreds of tapped holes for attaching valves; tapping all these holes can take several hours.

Because the machines are used in the food industry, most of the parts that are tapped are stainless steel. The requirements for surface quality are high, and only a few processes are permissible.

“Because there is always vibration when machining these large rings, the only thread generation process we can accept is thread tapping,” Mr Wagner comments. “Our designers call for 20mm tapped depth, that’s almost twice the depth usually required. This caused constant problems with swarf evacuation. The machine would run for twenty holes and then an employee had to stop the machine and strip out the swarf.”

The Garant Master Tap promised to solve this problem along with the potential to optimise the production of many smaller components.

“As well as the large steel rings we also make smaller components. Most of them are of stainless steel, but some are of aluminium and cast iron. Machining these various materials meant we regularly had to change the tapping tools which was really time-consuming.” Mr Wagner says.

So Krones didn’t just test the Garant Master Tap on tapping the stainless steel rings, but also on a variety of different materials.

“When tapping stainless steel rings, the Master Tap broke the swarf off cleanly at the root, so we no longer had to stop the production process to clear swarf which saved significant amounts of time. On the other hand, for the small components we used just a single Master Tap to tap well over 360 holes – applying increased cutting parameters at the same time. With the previous taps, because of the large tapped depth and the resulting swarf evacuation problems, for the same number of tapped holes we needed up to nine taps to do the same amount of work,” Mr Wagner affirms.

The Master Tap was also tested by Krones on other machines in sustained use: “The first impressions of the Garant Master Tap showed it to be a high-performance tap which delivers high process reliability in a range of applications.” Mr Wagner concludes.

Hoffmann www.hoffmann-group.com

Company

Hoffmann Group

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