m a n u fa ct u r i n g t e c h n o lo g y
the top of top coats FINIGARD topcoats were developed in the 1980s by Coventya to meet the increasing number of specific automotive requirements. Chromated zinc parts could not withstand the high temperatures encountered in an engine compartment and parts were showing very poor corrosion resistance when submitted to a tempering of 120°C or more.
T
he very first FINIGARD 100 was therefore developed to increase the corrosion resistance of chromated parts and to decrease the coefficient of friction of screws and nuts to facilitate or improve assembly, thanks to the use of a specific dry lubricant incorporated into the film. It immediately became obvious to the mechanicians that the coefficient of friction had to not only be reduced but also monitored within a very accurate and defined range to enable the automatic assembly of fasteners. FINIGARD 105 was developed in close partnership with the fastener industry in order to fulfil this requirement. This top coat, referenced worldwide, not only protects fasteners against corrosion but also ensures a perfect monitoring of the coefficient of friction in the 0.12_0.18 range. Today, the range of FINIGARD topcoats listed in the table below has grown to include more than 12 references that cover all requirements of the industry in terms of friction, aspect and corrosion resistance.
coefficient of friction
approvals
finigarD 105
0.15 +/- 0.03 (ISO 16047)
RSA, PSA, VW, GM, Volvo
finigarD 105 s
0.15 +/- 0.03 (Volvo)
Volvo
finigarD 107
0.06 – 0.09
finigarD 111
0.11 +/- 0.03
Audi/GM
finigarD 113
0.13 +/- 0.03 (DIN 946) on Zn/Ni
GM on Zn/Ni
finigarD 113 g
0.13 +/- 0.03 (DIN 946) on Zn
GM on Zn
finigarD 114
0.15 +/- 0.05
finigarD 115
0.15 +/- 0.03 (ISO 16047)
finigarD 150
0.15 +/- 0.03 (ISO 16047) on Zn/Ni & Zn
finigarD 450
0.17 +/- 0.03 (ISO 16047) on Zn
finigarD 460
0.17 +/- 0.03 (ISO 16047) on Zn
Volvo, Toyota
fom Zinthium 302
0.15 +/- 0.03 (ISO 16047) on Zn/Ni & Zn M8 screws
PSA, RSA
fom Zinthium 302 cf
0.15 +/- 0.03 (ISO 16047) on Zn/Ni & Zn > M8 screws
PSA, RSA
fom Zinthium 302 l
0.15 +/- 0.03 (ISO 16047) on Zn/Ni & Zn M8 screws
PSA, RSA
RSA, PSA
Most of these products can be used in both rack and barrel and several contain identifiable tracers to confirm conformance to specifications. In addition to improving corrosion protection and controlling/reducing friction, these finishes have overcome some of the most difficult surface treatment challenges faced by Coventya customers.
Case study 1: Use of lighter metals can lead to severe wear A major fastener supplier was faced with severe failure due to wear of an aluminium component mating against a very hard and nodular zinc nickel deposit. The problem was solved by the use of a PERFORMA 285 grain refiner to reduce the nodules and FINIGARD 150, a top coat with broad approvals from both Peugeot and Renault. FINIGARD 150 is highly adherent lubricant made up with a dedicated grafted polymer. It has a very dense yet permeable layer that provides heat resistance and self-healing properties.
Case study 2: New FINIGARD increases productivity A customer was struggling with inserting zinc electroplated self tapping screws into a steel assembly. The customer was obliged to use a dedicated lubricant on top of FINIGARD 105. Switching to FINIGARD 107, he was then able to obtain in a one step application the low tightening torque required. This result is not only valid for the tightening of steel but also works on softer materials such as aluminium. The tightening torque always remains low whatever the type of self-tapping screw. FINIGARD 107 technology applied on zinc electroplated screws reduced the tightening torque by more than 30% when drilling the screw into a hard and dry support like beech wood. It results in an increase of the number of screws that can be assembled by an automatic screwdriver, thus reducing the drudgery of this task for the workers.
122 Fastener + Fixing Magazine • Issue 71 September 2011