Productive Decoatingof PVD Coatings Platit CT decoats in less than one hour

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© Carl Hanser Verlag, München. 2014. All rights including reprinting, photographic reproduction and

translation reserved by the publishers.

Special reprint from Swiss Quality Production 2014

PLATIT AGEichholz St. 9 - P.O.Box 151CH-2545 Selzach / SO, SwitzerlandPhone: +41 (32) 544 62 00Fax: +41 (32) 544 62 20eMail: info@platit.comwww.platit.com

© Carl Hanser Verlag, Munich

P R E C I S I O N TO O L S

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> In May 2014, the importance, require-ments and latest technologies currentlyavailable were summarized in detail at aspecial workshop [2]. As a result, this ar-ticle can be spared a long introduction andconcentrate fully on the economically cru-cial question concerning the productivityof decoating.

›Productive decoating‹ actually soundsparadoxical. Decoating does not produce

any new product but removes an old, usedcoating so that the new coating can bondwell on the reground tool and achieve highperformance. Hence, productive decoat-ing primarily means speed. It must nothinder the production of the new coating.

Decoating processes and systems are of-fered by very few companies on the mar-ket. This knowhow is a closely guarded se-cret and is used predominantly only in theirown job coating centers. Very little data isknown about the individual processes. Itis a known fact, however, that decoatingtimes are long. They require several hoursor even days ([3], page 38).

Platit-CT decoating system

and process cycle

The new wet chemical decoating system(Figure 1) from Platit in Selzach/Switzer-land works with a free programmable,pulsed voltage supply that is controlled bya simple computer. The tools are held ininsulated fixtures (Figure 2). The process-es run in 2 electrolytic baths:■ Chemical A: for Ti, Al based coating

(acidic),■ Chemical B: for (Al)Ti,Cr (Cr, CrTi,Al-

TiCr) based coating (alkaline).The stability of the chemical baths is be-tween two and three weeks depending onfrequency of use. Constant new prepara-tion of the chemical baths is not necessary,which reduces the variable costs of the de-coating.

The process cycle is shown in Figure 3.In stage 1, pulsed decoating is performedin bath A or bath B. The decoating dura-tion is in minutes. Any thin TiN bondinglayer that might be present can be re-moved afterwards in a conventional de-coating module, under protecting voltage([3]), in peroxide solutions during stage2 within just a few minutes. Thus, the en-tire decoating process lasts considerablyless than one hour.

Platit CT decoats in less than one hour

Productive Decoatingof PVD CoatingsThe decoating of cutting tools for regrinding is an important precondition for their

recoating with high quality [1]. The methods known today are slow. This article presents

a new, fast decoating process and the decoating system developed for this purpose.

Figu

res:

Pla

titThe new Platit-CT decoating system1

BY BIRGIT WITTEL, CHRISTIAN

BÜCHEL, GUNNAR LAHTZ UND

TIBOR CSELLE

MANUFACTURERiPlatit AGCH-2545 SelzachPhone +41 32 5446200www.platit.com

■ for Cr based coatings,■ for Al, Cr, Ti based coatings.The recipes vary from each other for car-bide tools and HSS tools.

Figure 3 also shows carbide tools beforeand after the new Platit-CT decoatingprocess. For the user it is tremendously im-

The end of the decoating process can bedetected by the built-in electronics thatsimplifies the daily practice of the opera-tor greatly. This fast decoating also in-creases flexibility through the reduction ofthe decoating time. Its flexibility is of hugeimportance for small regrinders, they areincessantly struggling with large job coat-ing centers. The decoating process duringthe reprocessing of the tools no longertakes most of the time (collecting-decoat-ing-regrinding-recoating-delivering).

The decoating recipes

and decoated tools

The decoating recipes are the key to theprocess, of course. They include the fol-lowing knowhow:■ the recommended special holders for

shaft tools and hobs,■ which baths (alkaline or acidic) should

be used for the different coatings,■ the program for the electronic control

unit of the wet chemical processes (volt-age, current, frequency, duty cycle, op-erating time),

■ assessment of the surface quality andany further treatment that might be rec-ommended.

The recipes can be divided into 3 groups(Figure 3):■ for Ti,Al based coatings,

portant that the tools do not have any cobaltleaching, thanks to the TiN bonding layerand the two-stage decoating, and that thetool shafts cannot be attacked by the chem-icals, thanks to the specially sealed holders.They withstand the decoating without anydimensional changes.

Elements of thePlatit-CT decoatingsystem. Figure 2-A:schematic diagram, Figure 2-B: insulatedholder for shank toolswith power supplyingrails and with specialsleeves for protectingthe tool shafts,Figure 2-C: batharrangement

2

Process cycle of the CT decoating3

SWISS QUALITY PRODUCTION 2014 3

P R E C I S I O N TO O L S

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Birgit Wittel is Project Manager at Platitin Selzach/Switzerland

Christian Büchel is Product Managerat Platit

Gunnar Lahtz is Project Engineer at Platit

Dr. Tibor Cselle is Chief Executive Offi-cer of Platitinfo@platit.com

Comparison ofdecoating timesof solid carbideshank tools withconventional andCT process (forcoating thicknessof 2 µm)

4

1440

144

14

01

00TiN

420270

720

120

780

10

780

10

30

2400

10

2400

30

10

780

10

0404 04 04 04 04

30

TiCN-grey

TiAlN AlTiN CrN CrTiN-ML ZrN AlCrN AlTiCrN nACo nACRo

Dec

oatin

g tim

e [m

in]

ConventionalNew; stage 2New; stage 1

The productivity increase

As mentioned in the introduction, the pro-ductivity, the short execution time of thedecoating, is important so that the re-coating of the tools does not suffer any de-lay. Figure 4 compares, by way of example,the decoating times of the conventionaland Platit-CT processes for carbide shafttools. Caution: The diagram had to bedrawn with a logarithmic vertical axis dueto the enormous time-savings. ❚

REFERENCES

1 Prochazka, J.; Büchel, C.; Cselle, T.: Entschich-

tung gehört zum Beschichten. In: Werkzeugtech-

nik 11(2009), p. 40-44

2 Entschichtung von PVD-Schichten und Hy-

bridschichten. EFDS Workshop, Dresden 2014

3 Platit – Compendium 2014. 53rd Edition, Pla-

tit AG, Selzach 2014

4 Process for decoating ceramic hard coatings of

steel and carbide substrates. Patent application

PCT/EP2014/055376, European Patent Office,

Munich 2014

© Swiss Quality Production