Skin Design Companion

A companion toFORM STUDIES:

SKIN DESIGN

Viraj JoshiUG - Sem 5

MIT-Institute of Design

3 WEEKS

Introduction In our fifth semester as product design learners in MIT-Institute of design, in September 2012, this course was took place of what previously was a product-graphics course. Product-Graphics focussed on applying 2-D graphics and typography on the surfaces of products. However, the newly introduced course was ‘Skin Design’, or design of the entire material finish, exterior, or ‘skin’ of the product. I thank Prof. Sanjay Jain, HOD Product Design, MIT-ID and Mr. Aditya Dhawale, designer from Tata Motors, Pune, who conducted this course. Skin Design forms an essential part of Product Design as product skins are what people look at, take a feel of, before even looking at the function of a product. Even so, the skins have as much of a functional aspect to them as the aesthetic one. Depending on the application of the product, the skin has to have gloss finsih, matte finish, velvet finish, brushed finish or any other specific grain structure, depending on whether it has to be used by the hand, used only to look at and not to handle, etc. In this report, I aim to compile all the information from various sources, about different material finishes, how to achieve them, and their applications.

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Index

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The Skin Design Jargon 03

Quantifying or Measuring Texture 05 Grain Type 05 Grain Depth 06 Grain Scale 06 Average Surface Roughness Value 06 Equipments and Methods for Measuring Surface Finishes 07

Surface Finishes of Polymers 09 Textures on Polymers 09 In Mould Decoration 09 Hot Leaf Stamping 12 Pad Printing 12 Cubic Printing / Hydrographics 14

Surface Finishes of Metals 15 Polishing 15 Plastic Coating 15 Powder Coating 16 Enamel 17 Galvanising 18 Oil Blacking 18 Electroplating 19 Etching 20 Abrasive Blasting 20 Honing 21 Lapping 21

List of Product Material Finishes 22

Inspirations from Nature 25

References 27

The Skin Design JargonA-Surfaces: Those surfaces of a product which come in direct visual or tactile contact with a person are called A-Surfaces. These surfaces are the well finished surfaces and have a visual and a tactile appeal to the people who use them.

B-Surfaces:Those surfaces of a product which do not come in direct visual or tactile contact with a person, or the inner-surfaces of products are the B-surfaces. Generally, attention is not paid to the material finish of B-Surfaces, as they have no interaction with humans, and finishing these surfaces would incur unnecessary increase in costs.

Grain:The direction, texture, or pattern of fibers found in wood or leather or stone or in a woven fabric.

Interface:A point where two systems, subjects, organizations, etc., meet and interact.

Membrane:A pliable sheetlike structure acting as a boundary, lining, or partition in an organism.

Pattern:A repititive perceptual structure, in which each repeated element can be easily identified.

Skin:The thin layer of tissue forming the natural outer covering of the body of a person or animal.

Texture:The visual or tactile quality of the surface of any material is called a texture. One can notice a pattern, either regular or irregular in a texture, but identification of individual motifs is very hard. Textures are more interesting to feel than too see. Humans rely more on touch than on sight.

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A membrane or skin of a product is what not only holds the insides of the product together, but also gives it’s external tactile and visual appeal. It is very important for a product that one feels it, before buying and not only see it. Textures, surface finishes and product graphics are mostly used on the exteriors of the products, i.e. on A-surfaces, which is the surface that comes in visual and tactile contact of the user all the time.

In texture and skin design too, there is as much technology as there are aesthetics. A designer needs to probe deep into the manufacturing processes to achieve a certain texture and also the visual and tactile appeal of a skin.

An entire experience of a product is built only when all the senses of a human being work together. Humans rely most on the tactile sense and prefer touching a certain product before buying it. Feedback from the tactile senses is preferred to only visual feedback.

It is a general observation that matte surfaces, or surfaces with more textural details give more feedback than those with less texture. Thus grips, and areas of products with more tactile function are given a good, detailed texture with a high amount of grain depth. Textures have more than one function based on their applications: visual and tactile appeal, gripping, allowing a post process or the paint to be applied on the surface.

Plastic paints are generally inherent from the manufacturing processes and metal paints are applied through post processes.

Acquiring a texture in the manufacturing process of a product is the cheapest. The cost of the product increases as soon as a number of post processes are added to it.

How to decide the surface texture for a product?See where and how the product is going to be used.See the kind of interaction of the humans with the product.Consider environmental issues of product finishes.

Quantifying or Measuring Texture There are various methods to quantify and measure textures and surface finishes, and there are also many parameters that are considered while quantifying a texture. There are limitations of material, manufacturing processes, and costs, among many others to start with. The type of grain, the grain depth, the grain scale and surface roughness values are the most used methods of quantifying textures and surface roughnesses.

Grain Type:Grain type defines the texture of a product in terms of the shape or form of each motif or basic unit in the texture. Following are a few grain types: (Credits: www.forms-surfaces.com)

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Grain Depth:Grain Depth is the depth of the texture wall, or the difference between the highest and lowest levels in a texture. It is measured in standard units of measurement of distance. It is important to consider grain depth for products that have a heavy tactile usage. On repititive usage, their texture tends to erode by friction between the human’s body part and product’s surface. The deeper the grain depth, the longer the product takes to lose it’s texture even after heavy usage.

Grain Scale:Grain Scale is the scale of the pattern in a unit area. On increasing the scale, there is lesser detail in a unit area. Conversely, on decreasing the scale, there is more detail in a unit area of the surface of the product. This also decides the amount of friction between the product and the human being.

Average Surface Roughness Value:Surface Texture comprises of waviness, roughness and lay. Roughness is the vertical deviation of a surface from it’s real forms. Larger these deviations are, rougher the surface is. Waviness is the measure of the more widely spaced component of surface texture. The following graph explains the difference between waviness and roughness:(Credits: www.digitalmetrology.com)

Lay is a measure of the direction of the predominant machining pattern. A lay pattern is a repetitive impression created on the surface of a part. It is often representative of a specific manufacturing operation. The following are the different types of lays observed:(Credits: www.wikipedia.org)

Average surface roughness value, or Ra is the most used. It is the arithmetic mean of all the numerical values of heights and depths off a surface.(Credits: www.ifra.com)

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Equipments and Methods of Measuring Surface Finishes:The branch of science that deals with measuring surface finishes is called surface metrology. Profilometers are the equipments or machines used to scan a surface in order to quantify it’s roughness. They can be contact or mechanical ones, or optical ones.

Surface Finishes of Polymers

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Polymers, being synthesised materials, there are myriad surface finishes possible. Plastics are generally used for mass manufacturing and it is preferred not to have post processes, as that would increase the cost. Thus, most plastics utilise ‘In Mould Decoration’, or surface finishes and graphics inherent in the mould.

Textures on Polymers:To achieve a certain texture on the surface of a polymer part, the inner surface of the core and cavity is treated such that it gets the negative of the intended texture on the product. Thus, when the moulded product is ejected from the machine, it has an inherent texture moulded on itself. This texture is achieved by eroding the inner surface of the mould by EDM (Electric Discharge Machines) or etching. The inverse of this impression is achieved on the product surface after moulding.(Credits: www.cnmoulding.com, www.implant-mechanix.com)

In Mould Decoration (IMD) is a complex technology of surface printing, forming and moulding of a decorated film, which becomes an integral part of the final moulded product. The required graphics/symbols are printed on film prior to forming and moulding operations. The printed film is then formed and trimmed to required shape.forming the in mould decorated product.

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The moulding process consists of injecting the resin into mould cavity, which contains the printed, formed film. Once the resin contacts the film, the two materials fuse, fully encapsulating and protecting the inks, and forming the in mould decorated product. Through this process, there is no need for post - moulding decoration as pad printing. The technology is suitable for high wear applications extreme environment elements. The technology allows to print complex graphics on irregular / 3D surfaces. Graphics & colours can be changed as and when required. Environmental Friendly product since no adhesive in use. In Mould Decoration can be incorporated in many types of moulded components where decoration or identification is needed. (Credits: www.cpxinc.com, www.serigraph.com)

Silk Screen printing is the most used technology in printing the graphics. This 2D print is then translated onto the 3D surface of the mould by using various thermo-forming techniques. Cutting of the 3D film also happens inside the mould. Moulding of plastic part is then done. The foil can be manually or robotically placed into the tool depending on the volume required and the need for a fast cycle time. The molding process itself will almost certainly have to be optimized to suit the foil.

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(Credit: www.jujo-chemical.co.jp)

Equipments and Methods of Measuring Surface Finishes:The branch of science that deals with measuring surface finishes is called surface metrology. Profilometers are the equipments or machines used to scan a surface in order to quantify it’s roughness. They can be contact or mechanical ones, or optical ones.

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Hot Leaf Stamping:Hot-leaf stamping post processing is a decorating process in which a metal foil or pigment is placed on carrier films. A heated die is used to press against the foil and plastics, and the foil or pigment is released from the carrier film. It is the heat and the pressure of the process that bonds the decoration to the substrate.(Credits: www.universalmarking.com, www.toweradv.com)

Pad Printing:Pad Printing is used for printing across relatively small areas on plastic items and when the area to be printed is difficult to reach at or is contoured. This method uses a silicone ball/pad to lift the color and design off of a plate and then transfer it onto the surface of the item to be imprinted. An inked imageis transferred from a photo-etched plate to a thick, soft silicone pad. The pad is then pressed against the plastic part. The pad can wrap itself as much as 180° around a small object, and ink coverage is excellent. One color is done at a time, but registration between colors is good enough to allow four-color process printing.

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(Credit: www.padprintinginks.in)

Cubic Printing / Hydrographics:Cubic Printing is a decoration technology that uses a specialised film printed with a range of natural and abstract patterns to decorate complex shaped plastics, metals and other materials. The specialised film is floated on the water's surface and transfer of the pattern is effected by the pressure of the water. With this method, even decoration of complex three dimensional shapes is possible. (Credits: perodua.com.sg, www.p-wholesale.com)

Surface Finishes of Metals

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Finishes are given to any material for any one or more of the following reasons:1. To protect the material from moisture, wear, abrasion, fungus, mould or insect attack.2. To change the material appearance, it’s colour or texture.3. To enhance the material durability, surface hardness or any other of it’s properties.

Polishing:•Polishing increases gloss or shine of a product.•This is achieved through an action of rubbing or application of chemicals on the surface. Polishing has to be done regularly to maintain shine.•Buffing or using chemicals are types of polishing.•Lacquer can be applied to protect polished surface.(Credits: www.tech-rhet.net, www.implant-mechanix.com)

Plastic Coating:•For plastic coating, the metal object is heated to about 150 degrees celcius, and dipped into fluidises powedered plastic.•This plastic melts onto the surface of the metal.•This method is used mostly to coat handles of objects.

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Plastc Coating: (Credits: www.youtube.com, www.componentforce.co.uk)

Powder Coating:An electrostatic gun is used to spray a powder that has an electric charge. This powder is sprayed onto a metal part who’s surface has to be coated and is grounded. Thus, through electronic attraction, the powder sticks to the object. The object is then heated allowing the plastic to stick to the surface of the metal. The powder used here is a thermoset or a thermoplastic polymer.(Credits: www.advanceindustriesgroup.com www.made-in-china.com)

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Powder Coating Process (Credit: www.colourspray.com)

Enamel:Enamels are materials made by fusing powdered glass to a substrate by firing, usually between 750-850 degrees celcius. The powder melts, flows and hardens around a material’s surface and becomes smooth.(Credits: img.ffffound.com, www.topcreas.ro)


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Galvanising:Galvanization is the process of applying a protective zinc coating to steelor iron, in order to prevent rusting. Although galvanization can be done with electrochemical and electrodeposition processes, the most common method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc.(Credits: www.unicodirect.com, www.tom-parker.co.uk, www.galvanizeit.org)

Oil Blacking:Steel is blackened with heat, chemicals or a combination of both. Steelhas two oxides: red and black. Red oxide is what we know as rust. It is corrosiveand destructive. Black oxide provides a protective, abrasion-resistant coatingthat prevents rust formation. Depending on the method used, black oxide can beapplied in an even finish.


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Oil Blacking: (Credit: www.rockseven.com, www.photobucket.com)

Electroplating:Electrodeposition of a metal or alloy from a suitable electrolyte solution is called electroplating. The article to be plated is connected as the cathode in the electrolyte solution; direct current is introduced through the anode which consists of the metal to be deposited. In this method, chrome, nickel can also be plated onto surfaces of other metals.(Credit: en.wikipedia.org, www.nij.gov)

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Etching:Etching is the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in the metal.(Credits:www.making-jewelry-now.com)

Abrasive Blasting:Abrasive blasting or commonly known as "Sandblasting" is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface, or remove surface contaminants. Types: Wet Abrasive Blasting (use of hot soap water), Bead Blasting (blasting of glass beads), Wheel Blasting (does not require a fluid for the blast) and Micro-Abrasive Blasting.(Credits: www.ronclamp.com,

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Honing:Honing is the surface polishing technique for metals in which the insides of cylindrical objects are surface finished. The honing tool makes use of abrasive stones or diamonds at times. By this methods, material is removed at micron levels.(Credits:www.alsonshydraulic.com, www.aa1car.com)

Lapping:Lapping is an abrasive process that removes the last bit of unwanted material. A lapping process sometimes uses an abrasive paste that is rubbed across the part to gradually smooth it.(Credits: www.suntechnocraft.com, www.soundonsound.com)

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List of Product Material Finishes

Glossy Matte

Brushed Stippled

Chrome Rough

Galvanised Metal Rusted Metal

Metal Floor Embossed Rubber

Rubber Leather22

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Etched Patterns Embosses

Ice-Finish Kevlar/Warp-Weft Finish

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Inspirations from Nature

ReferencesThe Wordweb DictionaryThesaurus.comhttp://www.researchandmarkets.com/reports/224971/in_mould_decoration_of_plastics.pdfhttp://eschmanntextures.com/pt/area-automovel/guia-textures-online/determination-of-the-grain-depth/http://www.m-techindia.com/html/unit4.phphttp://www.toolingu.comhttp://www.blender.orghttp://www.zcars.com.auhttp://i-cdn.phonearena.com0.tqn.comcgtextures.comflickr.comhttp://www.colourbox.comhttp://static5.depositphotos.comhttp://image.shutterstock.comhttp://image.yaymicro.comhttp://www.torange.ushttp://fc07.deviantart.nethttp://cloud.graphicleftovers.comhttp://www.hwsands.comhttp://www.imageafter.com

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Skin Design Companion

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