Home keyboard_arrow_right Manufacturingkeyboard_arrow_right Productkeyboard_arrow_right Feature

Sewing Athletic Shoe Upper

by Apparel Resources

01-November-2008  |  25 mins read

With more people across the world taking to a healthy lifestyle, the market for athletic shoes is on the increase; more so as the segment which was earlier just about sports now has a growing segment of ‘active’ and ‘fashion’ wearers. In fact, according to the market research group NPD, in the $ 19.4 billion athletic footwear market, running shoes is the largest selling category ($ 4.9 billion) followed by low performance footwear designed for fashion and comfort ($ 4.8 billion).

shoe-new

“Team StitchWorld approached one of the largest footwear manufacturers of India, Liberty, to learn more about the technology behind the making of an athletic shoe and was subsequently given exclusive rights to visit and shoot their factories. Footwear Design & Development Institute (FDDI) also opened its doors for the team to share their expertise in the field.”

Process flow
Process flow

The athletic segment in shoes is dominated by innovations for greater comfort, performance and look. Research has reached a stage where efforts are on to transform footwear into a dynamic and active foot-device capable of adapting to the users environmental conditions for better foot health. European Confederation’s — the Comfort Environmental and Custom (CEC)-made Shoe Integrated Project, aimed at the development of radical innovations, is targeting to come up with ‘no last’ shoe – manufactured without lasts, the ‘seamless’ shoe and the ‘eatable’ shoe-manufactured from 100% environmentally-friendly materials.

However in the near future, experts predict refinement of current designs rather than radical breakthrough.

  • Within the next couple of years the athletic shoe sizing will become standard world wide.
  • Designers will continue to seek light weight materials that provide better support and stability with further use of gels and air systems.
  • Electronic components will also be built into the running shoe so that information about physical characteristics and development can be recorded with microchip and later downloaded into computer.

Technical Fabrics for the Uppers

An ‘upper’ made of improved water-repellent rip-stop soft shell material, perforated foam, breathable… athletic shoes offer a multitude of choices to a manufacturer to experiment with fabrics. Any kind of woven fabric could be used as outer shell if it is strong enough to resist abrasion and tearing forces. While, for the outer shell, flat fabrics with linen weave or twill are most popular, for trimming, fake furs and plush make an interesting choice. The lining is popularly of woven or knitted fabrics, which are sleek in the case of athletic shoes. Some manufacturers also use terry type fabrics for the rim of the ankle.

Production line for stitching of shoe upper
Production line for stitching of shoe upper

The choice of technical fabrics for the uppers are many depending on their functionality. The fibres for the textile materials are mostly polyester or polyamide. Laminated foils are being used to keep water out. Next to the classic brands like Gore Tex/USA and Sympatex/Germany, there are many other products available, which allow moisture transportation from inside out and prevent wetness to come in from outside. A new development is a fully recyclable membrane with Oeko Tex-Standard 100 certificate: Sympatex launched its PUR (polyurethane) membrane in 2007.

Today, outer fabrics made of spacer warp knits are in fashion and used for airy summer athletic shoes. These warp knit spacer fabrics are known for their thickness, which varies from 2 to 16 mm. The top surface often shows an open wafer structure while the inner surface is neat and plain with the ability to decompress. These fabrics give a rather bulky look to the shoes.

Sole stitching
Sole stitching

Another focus area is the sole: The sole must absorb bumps and give a good grip on the ground. Cushions with air or gel, special inner and outer structures provide these functions. For moisture transportation through the sole, tiny holes in the sole are combined with membranes. This high-end technology is expensive but solves the moisture transportation in insoles. The insoles are made of laminated materials like foams and are covered by textiles. The anatomically formed insoles which absorb shocks, support the arch of the foot and drain moisture from the foot and the sock. Insoles could also be finished with anti-bacterial treatments.

How seriously the footwear companies take to new developments in this segment can be gauged from the fact that Adidas spends up to $ 100 million in sports shoe research every year. The research for them begins with motion capture where an athlete’s foot is tracked to see how it moves while running or jumping. This information is then used by the resident technologists to identify raw materials for manufacturing the shoe – flexible materials for stress points, firmer for areas that need support or breathable material around areas that sweat a lot.

Robotic lasting with heat setting
Robotic lasting with heat setting

The research goes on to identify different plastic spheres for different applications for use in heals and toes to give extra bounce to one area and limited bounce to other area to fit the specific need of the specialized sport. A shoe designed for rock climbing will have distinctly different durability needs than a shoe designed for basketball, which requires extra bounce in the toes and should drop flat at the heels.

Growing World Market

The fast growing global footwear market supports the magnitude of research going into athletic footwear. Estimated footwear industry worldwide by 2010 is pegged at US $ 192.4 billion with a projected consumption of 13.9 billion pairs of shoes. Without doubt the US now leads the global footwear market with approximately a-third of the total demand. While China exports close to a billion pairs a year, India exports just 100 million pairs annually.

The Feiyue FY9910 model used in sewing of upper and lower leather
The Feiyue FY9910 model used in sewing of upper and lower leather

According to Global Industry Analysts Inc. (GIA), Asia Pacific (excluding Japan) is projected to be the fastest growing region showing a compounded annual growth rate of 4.8% from 2001-2010. China, India, and also Latin America are experiencing amazing growth as footwear manufacturers compete for the price-conscious consumers to spend on their favourite international brands. Today the Asia Pacific market is the largest in volume with casual footwear the fastest growing and largest product segment. An estimated 7 billion pairs were sold in 2006.

According to the Council for Leather Exports, India accounts for 2.65% of the world trade in leather and leather goods generating business worth US $ 1,210 million in the year 2007-08 in leather and non-leather footwear (excluding footwear components). For the co-relating period, India exported an estimated $ 900 million worth of footwear to Europe where UK was the top market with $ 215 million, followed by Germany with $ 205 million. Surprisingly, USA comes much down in the list with $ 162 million, with the balance $ 148 million to the rest of the world. (Source: CLE & US Customs).

The over seaming machine 141-23 EV from Strobel
The over seaming machine 141-23 EV from Strobel

Manufacturing Shoe in India

Though India has traditional footwear industry centred in Tamil Nadu, Agra, Kanpur and Delhi, it is only recently that international brands have started using the country as a manufacturing base for athletic shoes. Nike, Adidas, Puma, Reebok, Fila and New Balance are using India as a production centre through outsourcing contracts with domestic companies such as Lakhani Arman Group and M&B Footwear and Sports Stations for Nike. Whereas Adidas is using Liberty & Moja shoes for its demands, domestic players like Bata, Liberty, Mirza, and Woodland also have major presence in footwear market.

Indian production capabilities in footwear has seen impetus with many new projects involving international players and dedicated SEZs. Apache Footwear Ltd., a China-based company and the largest manufacturer of Adidas shoes worldwide, recently signed an agreement with the Andhra Pradesh Government to set up a manufacturing facility on a 314-acre site, which has been accorded SEZ status. The company plans to manufacture one million pairs of shoes annually at the facility.

The PFAFF 3371-1-11 bartacker machine
The PFAFF 3371-1-11 bartacker machine

IndKunz Shoe Last Development (India) Pvt. Ltd., a wholly-owned subsidiary of Formas Kunz, Brazil, is setting up a shoe last manufacturing unit at Irrungattukottai, about 40 km west of Chennai, for the domestic and export markets.

The development of three exclusive footwear SEZs – Apache SEZ Development India Pvt. Ltd. (Andhra Pradesh), Cheyyar SEZ (Thiruvannamalai, Tamil Nadu) and State Industrial Promotion Corp. of Tamil Nadu (Sriperumbudur) at a time when the Chinese shoe industry might actually be showing a slowdown is exciting news for the Indian industry, providing a new opportunity for growth.

Stitching Technology for the ‘Upper’

  • The cutting of uppers and linings is the first step in shoe construction which involves die cutting the shoe parts in cookie cutter fashion using hydraulic pressing machines. These parts are then stitched or cemented together to resemble 3D structure and finally fitted on a last to give the shape. 
  • The number of operations may vary from as few as 15 to as many as 60, depending on the style and the number of cut components. 
  • While the upper is being fitted and assembled, other parts of the shoe, such as insoles and outsoles, welting, counters which are molded to the shape of the last, and which reinforce the shoe and preserve its shape, heels, and toe puffs, are prepared. 
Process Flow Chart for Stitching Athletic Shoe Upper-Duerkopp Adler
Process Flow Chart for Stitching Athletic Shoe Upper-Duerkopp Adler

Sewing Machines

Sewing shoe upper involves intricate 3D motifs using stiffer and thicker material. The special machinery features for shoe upper sewing are: post bed/cylinder bed, compound feed/unison feed, alternating top feed mechanism and roller presser foot/roller feed dog. The post and cylinder bed machines work on average between 2400 spm to 3000 spm and comes in variety of feed systems in combination with wheel feed. The automatic back-tacking device ensures a “stich-in-stich” back-tacking. Automatic thread trimmer, presser-foot lift and back-tacking with push-button contribute to its high productivity. Other machines used are zigzag, pattern taking, insoling and also flat bed machines. Programmable pattern tacking machines are used for decorative stitch, decorative patch attach and other cycle operations. Specialized over seaming machines are used for insoling purposes.

Pattern Tacking

The PFAFF 3371-1/11 model is an electronic lockstitch bartacker for heavy materials with a new S3 control panel with integrated data reader for transferring sewing programmes and machine software. It offers a direct selection of 40 standard bar tack types with short, cut thread ends and gives high productivity due to short cycle times. There is no requirement of compressed air as the functions are electro magnetically controlled.

Overseaming

The over seaming machine 141-23 EV from Strobel capably sews insoles to uppers. This machine sews leather or textiles up to a thickness of 7 mm. Its gathering device helps to sew in fullness of the upper. Optional equipment (different feed and front cups) enables the machine to manufacture children shoes or very delicate material.

Even kits for string lasting (with strings from 1.7 mm to 2.5 mm diameter) or for California-type shoes and a thread lubricator are offered. In fact, Strobel is the inventor of this technique of insoling. In relation to the conventional lasting method the Strobel-method saves quite a lot of material.

Process Flow Chart for Stitching Shoe Uppers – Sunstar
Process Flow Chart for Stitching Shoe Uppers – Sunstar

The 410-1 EV is a heavy machine used for stitching insoles to uppers. Even hard and stiff leather or textile material up to a total thickness of 8 mm can be manufactured easily. As both the feed cup and the front cup of this machine are driven, bulky material can be sewn evenly. The differential feed (the speed of the front cup is adjustable while sewing up to 48% in comparison to the speed of the feed cup) and the gathering device enables to level up unwelcome distortion or to work in extra fullness even at bulky leather.

Post bed

Feiyue FY820H model and Golden Wheel CS – 5361 N are single needle post-bed heavy-duty sewing machines. Both give excellent sewing effects thanks to vertical rotating hook, the link take-up lever and lock stitch with drop feed on both thin and thick materials. The thick needle provides more strength and stability in sewing and works well for sewing on closed uppers of thick materials.

The Feiyue FY9910 model is a single needle post-bed sewing machine with double-wheel and its needle feeding facilitates smooth operation of upper and lower leather, ensuring continuous supply of leather or fabric. The combined action of wheel and press foot ensures constant stitches in both thick and thin sewing operation, whether it moves straight forward or makes turns. When spongy material is sewn, it does not crinkle or deform; instead, it is sewed very smoothly and neatly.

The Highlead GC24608-2 model is a post bed twin needle walking foot lockstitch machine which is useful for sewing shaped items or panels that cannot be done on a standard flat-bed machine. The 178 mm high slim post bed gives greater access and control when sewing shoe uppers. The machine also features a heavy duty triple feeding action by way of: bottom feed, needle feed and walking foot top feed and is fitted with two large vertically mounted hook and bases for use with medium to heavy weight materials.

KM-957 from SunStar is a roller-driven post bed series which enables smooth stitching at corners and maintains a constant quality of sewing, no matter what kind of fabric, due to accurate feed by the roller presser foot and wheel feed dog. The secure thread trimmer guarantees clean operation, whether thin or thick thread. With the thread tension adjusting device, this machine can easily sew thin, medium as well as heavy fabrics even at high speed of 3,500 spm.

The new Duerkopp Adler post bed 888-160122 M-Type series, with its outstanding performance parameters, is setting new standards in stitching operations in the shoe production. In conjunction with the needle feed and the driven roller foot, the double feeding of the wheel bottom feed ensures quiet and smooth sewing with exact stitch length, even when sewing over extremely thick areas.

Sewing shoe upper involves intricate 3D motifs using stiffer and thicker material. The special machinery features for shoe upper sewing are: post bed/cylinder bed, compound feed/unison feed, alternating top feed mechanism and roller presser foot/roller feed dog.

Cylinder bed

The Highlead GC2698-1 model is a cylindrical bed compound feed lockstitch designed with a small radius cylinder bed and a compound feed mechanism. The small radius cylinder bed allows easy access to sew on items like thin leather garments, shoes, slippers and for binding on seat cushions and similar operations. It is available in three subclasses to meet different requirements. The built-in bobbin winder is on the side of the head for easy access and the presser foot lift is adjustable up to 14 mm.

Golden Wheel CS – 335 BH single needle, cylinder bed sewing machine with unison feed has horizontal movement of drop feed for binding operation. It is suitable for taping, piping or binding of medium and heavy materials, e.g. bags, shoes, purses and other tubular goods. The binder feeding together with unison feed ensures uniform feeding of fabric even on materials with rough, slippery or tacky surfaces. Its cylinder bed diameter is 46 mm which enables easy and unhindered movement of bulky or tubular workplace.

Zigzag

Duerkopp Adler 525-101 model with exchangeable cams is used for decorative seams with exchangeable cams for light to medium weight material. The parallel slide of the needle bar ensures a straight stitching of the needle into the material and allows a higher speed and accurate stitch formation. Automatic lubrication, integrated bobbin winder, large hook with high bobbin thread capacity, large zigzag stroke and the adjustment possibility of the stroke are the main features of this machine range. It offers sewing equipments for butt-joining seams on shoes with nose for guiding or a cording seam in 7, 5 or 4 mm seam margin as well as for binding operations. Pattern cams in 18 different designs are available and can be changed in shortest time. The machine moves at a maximum speed of 4400 rpm.

Pattern sewing

Sunstar SPS/E-1507HS-20 is an electronically-controlled pattern sewing machine. Moving at a high speed of 2700 spm this machine gives an outstanding productivity. The installation of Fortuna IV 550W gives a high needle penetration so that the machine has sufficient power to handle sewing of heavy materials. The operator can easily adjust the height of the feeding plate as per the sewing conditions. With full cross control, the X-Y feed can be adjusted at a unit of 0.05 mm. This enables precise and delicate sewing and also the sewing of difficult slant lines and curves. According to the thickness of sewing materials, the presser foot height can be adjusted. Consequently high quality is guaranteed for sewing materials whose thickness is different.

Flat bed

Seiko THM-26B is a 2 needle extra heavy duty machine which gives multiple choices in ornamental stitching: It can make 5 different patterns. This is a flat bed, lock stitch machine with a large shuttle hook and an automatic presser foot and is ideal for sewing heavy weight materials such as canvas, vinyl, leather, synthetics and rubberized fabrics, various coated, laminated fabrics, etc. It is suitable for stitching operations in sofas, tents, shoe uppers, suitcases, bags, etc. Additional features include capability to do reverse option and easy change of the cam. A cord insert option is also available.

Seiko LSWN-48BL and 46BLR (patent pending), are 4 needle, high speed flatbed lockstitch machines with large vertical axis hook for reverse stitch and compound feed that are used for sewing medium weight fabrics, leather, vinyl, synthetics and laminated and coated materials for products such as upholstery, sports and camping equipment, apparel, and footwear. The machine has a feed-adjusting dial which easily determines the process of stitch length. It ensures an advanced penetration for sewing of thick material/adoption of large pulley (O.D. 150 mm) which enables the needle bar to be positioned properly. It has standard equipment for long stitch (max.10 mm) suitable for thick material with variable speeds depending on threads, materials and type of operation.