Acceptance Criteria for Painted Surfaces Inside and Outside Of

Illustration by Peter F. Salvati; photos courtesy of the author

By Dr. Christian Amorin Alstom Transport SA Petite Forêt, France Acceptance Criteria for Painted

Surfaces Inside and Outside this case, travellers, for whom such things as timetables, prices, and the of Railway Vehicles cleanliness and comfort of the railway vehicles are important. Aesthe- ainting represents less than throughout Europe, initiated a study tics are part of this, but not essential. 10% of the cost of a railway about a standard quality level for all Therefore, the notion of “zero aes- P vehicle, which may seem its European facilities in 1995. This thetic failure” (i.e., paint blemishes) insignificant, but the work actually article describes the quality control is not a critical satisfaction factor. is quite significant both in terms of procedures developed as a result of Instead, the first and primary the protection against corrosion as that study and the acceptance crite- requirement of a railway network is well as the aesthetic value it pro- ria the company now uses for the reliability, which is related to coat- vides for rolling stock. painting of railway vehicles. ing quality in terms of the long-last- Furthermore, quality control in ing anti-corrosive protection it pro- coating railway vehicles is impor- Alstom’s Quality Standard vides, thereby helping to keep the tant, because if the work is not Among the expectations of a rail- railway vehicles strong and safe. done properly, they will need to be way vehicle manufacturer are that This is reflected in the following repainted, which will mean higher the rolling stock it makes will remain basic postulate of the Alstom costs, longer delivery times, and safe throughout its lifetime, that its Transport quality standard: possibly more impact on the envi- vehicles will have a visual identity, • Coating quality must retain its ronment, depending on the types and that they will be both aestheti- long-lasting anti-corrosive and of coating materials used. cally pleasing to look at as well as strength properties. For these reasons, Alstom comfortable for travelers to use. • Any alteration of a coating that Transport SA, a railway vehicle Railway companies, like any indus- would affect these properties must manufacturer with facilities try, must please their customers—in be corrected.

34 PCE January 1999 Copyright ©1999, Technology Publishing Company Quality Control Procedure Table 1: Acceptance Criteria for the Outside of Railway Vehicles for Outside Surfaces Failure type Criteria Outside surfaces include the Non-quantifiable Failures external surfaces of the vehicle and Colour difference Visual comparison with standard samples fittings positioned on the outside. Agreement of the railway vehicle manufacturer’s quality department The control procedure described Spectrometric measurement if necessary here should be done when the Gloss difference Direct gloss: vehicle is finished. Any measures Average deviation not more than 10 points, compared with needed to conform with the basic customer’s specification, with peaks not higher than 15 points postulate and to correct coating (measurements at 60-degree angle) conditions that do not match the Varnished paints: Average deviation not more than 5 points, compared with acceptance criteria defined below customer’s specification, with peaks not higher than 10 points should be taken before this control (measurements at 60-degree angle) procedure occurs. Mottling of Satisfactory aesthetic value in conformity with the railway vehicle Inspection requirements needed metallic paints manufacturer’s quality department for such a control are as follows: Sanding failures Conformity with gloss measurement • means: with naked eye (corrected or marks with eyeglasses if necessary); Sagging Not acceptable • distance: 1–1.5 metres; Holidays Not acceptable • height: from the height of the Satisfactory aesthetic value in conformity with the railway vehicle railway platform; Orange peel Overspray fallout manufacturer’s quality department • inspection: on foot, walking at a Conformity with gloss measurement speed of about 1 metre/second; and Checking Not acceptable • lighting: 400 lux ± 20%. Superficial pollution Not acceptable According to the methodology of (i.e., adhesive traces, the quality control procedure, the humidity marks, etc.) inspector walks along the railway vehicle without stopping. If a fail- Quantifiable Failures * ure (see the list of possible failures Scratches Length less than 30 mm or defects in the section below on Impacts Surface smaller than 30 mm2 Acceptance Criteria) is detected, a Curtaining Not acceptable if located on an open surface; otherwise: mask with a 400-mm circular open- • length less than 50 mm ing is placed on the painted surface • width less than 7 mm with the failure or defect in the • thickness less than 1.5 mm middle. The distance between two Pinholes No more than five failures of any type within a circle of 25 mm masks is 1 m minimum, except for Micro-foaming diameter (every such circle counts for one failure) pinholes, micro-blistering, dust, and Dust and inclusions inclusions. The quantifiable defects Fingerprints Satisfactory aesthetic value in conformity with the railway vehicle manufacturer’s quality department are then counted. The acceptance criteria for both * Total criteria for quantifiable failures: no more than five failures of any type seen within the mask quantifiable and non-quantifiable coating defects on outside surfaces of railway vehicles are included in tural parts remaining visible after • Type 2—parts or surfaces inside Table 1. complete arrangement inside the technical areas; and vehicle. • Type 3—non-visible parts. Quality Control Procedure Three types of interior parts or Control of Type 3 parts is made for Inside Surfaces surfaces include before assembly; control of both Inside surfaces include fittings • Type 1—parts or surfaces visible other types of parts is made after found inside the vehicle and struc- to travellers; assembly. As in the case of the

Copyright ©1999, Technology Publishing Company PCE January 1999 35 Table 2: Acceptance Criteria for the Inside of Railway Vehicles assembly of the railway vehicle are as follows: Failure type Criteria • means: with naked eye (correct- Non-quantifiable Failures ed with eyeglasses if necessary); Type 1 Pieces and Type 2 Pieces Type 3 Pieces • distance: 1–1.5 metres; Colour difference Visual comparison with standard samples Acceptable • inspection: stationary (standing Agreement of the railway vehicle manufacturer’s in front of the area to be inspect- quality department ed); Gloss difference Direct gloss: Acceptable • lighting: 400 lux ± 20%. Average deviation not more than 10 points, Likewise, inspection require- compared with customer’s specification, with ments after assembly of the rail- peaks not higher than 15 points way vehicle are as follows: (measurements at 60-degree angle) • means: with naked eye (correct- Varnished paints: ed with eyeglasses if necessary); Average deviation not more than 5 points, compared with customer’s specification, with • height: from positions standing peaks not higher than 10 points in the gangway and sitting on a (measurements at 60-degree angle) seat; Mottling of Satisfactory aesthetic value in conformity with the Acceptable • inspection: walking continuously metallic paints railway vehicle manufacturer’s quality department in the gangways at a speed of Sanding failures Conformity with gloss measurement Acceptable about 1 metre/second and sitting or marks on a seat for about 5 seconds; and Sagging Not acceptable Acceptable • lighting: as provided by the Holidays Not acceptable Acceptable inside lights. Orange peel Satisfactory aesthetic value in conformity with the Acceptable According to the methodology of Overspray fallout railway vehicle manufacturer’s quality department the control procedure, the inspec- Conformity with gloss measurement tor walks along the gangways with- Checking Not acceptable Not acceptable out stopping or sits in a seat at Superficial pollution Not acceptable Acceptable random. If a failure or defect is (i.e., adhesive traces, detected, it is identified and quan- humidity marks, etc.) tified. A mask with a 200-mm circular opening is placed on the Quantifiable Failures * zone, with the failure in the mid- Scratches Length less than 30 mm Acceptable dle. The distance between two Impacts Surface smaller than 30 mm2 Acceptable masks is 0.5 metre minimum, Curtaining Length less than 50 mm Acceptable except for pinholes, micro-blister- Width less than 7 mm ing, dust, and inclusions. The Thickness less than 1.5 mm quantifiable defects are then count- Pinholes No more than five failures of any type within a Acceptable ed. The acceptance criteria for both Micro-foaming circle of 25 mm diameter (every such circle quantifiable and non-quantifiable Dust and inclusions counts for one failure) coating defects on inside surfaces Fingerprints Satisfactory aesthetic value in conformity with the Acceptable of railway vehicles are included in railway vehicle manufacturer’s quality department Table 2.

* Total criteria for quantifiable failures: No more than 10 failures of any type seen within the mask Acceptance Criteria control procedure for outside sur- do not match the acceptance crite- Following are brief definitions of faces, any measures needed to con- ria should be taken before this con- the main types of failures or form with the basic postulate and trol procedure occurs. defects that occur in painting to correct coating conditions that Inspection requirements before work, classified into two cate-

36 PCE January 1999 Copyright ©1999, Technology Publishing Company gories: quantifiable and non-quan- Quantifiable Failures or Defects • in Germany: Salzgitter. tifiable. When a failure or defect is • Scratches: marks made on a The Alstom method also has found, the acceptance criteria for paint film by foreign objects. been discussed by the French painting work inside and outside • Impacts: dents. Standardisation Commission and railway vehicles should be checked • Curtaining: localised slipping of adopted by commission members to determine whether a repair is the paint film that may result from (Bombardier Transport, De Dietrich needed or not. an excess of paint on an uneven Ferroviaire, SNCF, and RATP) for surface. The excess material con- insertion in French AFNOR Non-quantifiable tinues to flow after the surround- Standard F 19-141 (Railway Failures or Defects ing surface has set up. Rolling Stock: Protection and • Colour difference: perceptible • Pinholes: very small holes Ornamentation by Painting of Car colour difference due to overspray appearing in the paint film during Body and Component Parts–Part 1: deposit, application conditions, application and cure, generally due General Prescriptions), which too heavy film thickness, etc. to air or gas bubbles in the wet relates to protection and decoration • Gloss difference: perceptible film that create small pores when through painting. gloss difference due to spraying evaporating. conditions, too much thickness. • Micro-foaming: small pores creat- Conclusion • Mottling of metallic paints: per- ed by bubbles bursting in a partial- The concept of control outlined ceptible non-homogeneous distrib- ly dry paint film. in this article meets the needs of ution of metallic particles in the • Dust and inclusions: foreign par- both customers and builders of rail- film. ticles trapped in the paint film or way vehicles. Indeed, by not requir- • Sanding failures or marks: per- fastened to the film surface. ing over quality (i.e., “zero aesthet- ceptible marks made during sand- • Fingerprints: marks printed in ic failure”), the cost of painting ing work. the film before its complete solidifi- work can be optimised, resulting in • Sagging: movement of the paint cation. better cost controls and increased film between application and investment capacity for railway cure. Sagging is generally limited Industrial and operators. to a localised zone on vertical Standardising References surfaces. The above control concept was Acknowledgements • Holidays: localised zone from worked out by Alstom Transport The author wishes to thank the which paint creeps aside, leaving painting experts throughout Europe experts of Alstom Transport who a surface with partial or total lack and resulted in two in-house stan- have worked on this subject: D. of protection. Holidays may be dards being developed by the com- Brown, H. Schroll, M. Espuelas, L. due to pollution or insufficient pany: Querol, P. Lucas, Ch. Delgrande, surface preparation. • DTR.1 029, Acceptance Criteria and R. Villemin. Also, a special • Orange peel: surface condition for a Painted Car, and thanks to R. Zaun of De Dietrich that creates a texture similar to an • DTR.1 032, Acceptance Criteria Ferroviaire for his contribution. orange peel. for Painted Parts Located Inside a • Overspray fallout: fine overspray Car. This article is based on a presenta- deposit on an already dry film. These standards are used by all tion at ECOLROMAT ’98, which • Checking: fine cracks that do Alstom Transport facilities special- was held 8–9 October 1998 at not penetrate the topcoat but ising in assembly, namely those Mulhouse, France, and published spread superficially, resulting in a located in the conference proceedings. It is crocodile skin-like texture. • in France: La Rochelle, Belfort, used here with the permission of • Superficial pollution: remnant of Valenciennes; the organisers. other treatments, such as gluing, • in Spain: Barcelona, Valencia; surface glazing, masking adhe- • in Great Britain: Birmingham; sives, etc. and