ciatec calzatecnia pdf eng

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Technical and economical overview

of footwear technologies

1. Introduction

The economic environment is even more uncertain and the footwear industry is subjectto constant pressure and change.

Consumers demand more innovative products of higher quality and lower price, evenwhen leather and other footwear materials, as well as the cost of labour are increasing.

The demand for cost reduction is the main driver for the footwear sector.

The overall cost to manufacture a shoe in the Europe (with differences in each country)indicates that labour, material and manufacturing cost constitute 75 % of the total cost.(Table 1

Table 1: Structure of shoe cost in EuropeLabour cost 40Materials/components/manufacturing 35Overhead costs + commercial & publicity 15Installations and equipment 5Profit and sales costs 5Total cost of shoe 100

Easy it is to conclude the advantages of the cheap labour countries in the footwearproduction. The result has been the gradual and continuous decrease in the productionof footwear in the European Union and the USA.

The automation and technology modernization can reduce significantly the directproduction costs. But in some cases the indirect costs are not affected: programmingand maintenance, productivity control operations can even increase them.

The labour costs put the US and European manufacturing firms under great pressure.

Consumers have the decisive role. They will not pay the same price for an identical shoecommercialised by a Latin American Company or by an USA or European one.

Within this competitive scenario, the strategic decision of which kind of articles can beproduced competitively, in short and in medium/long term is fundamental. Factors likecountry image, manpower skills, existence of materials and component suppliers, size ofinternal market, play an important role in that strategy limiting the scope of footweartypes to be produced.

Footwear manufacturers tend to implement a strategy linked to the production of eithermassive or fashion articles. If they had success they begin to create its own identity andimage.

Their brand image, marketing, management and organization skills, production andprocess competencies, product characteristics will limit and/or strength their competitivestatus. Any strategy once adopted cannot be easily abandoned.


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The most standardized articles can be copied and manufactured in large quantities bysemi-skilled workers in low cost countries.

Some companies in developed countries compete vigorously with standardized productswhile others specialize in sophisticated and fashionable ones. The great majority,usually small and medium, concentrates mainly in manufacturing, although a few ofthem try to sell directly to retailers and consumers.

Some others are not merely manufactures, but they are mainly involved in distributionand commercialisation, coordinating value added chains stretching from design toretailing. These companies were well succeeded in establishing efficient plants in labourcheap countries, namely for sport shoes and other standard shoe models. These plantsuse unskilled or semi-skilled labour and traditional technologies.

To compete with these low cost producers, manufactures in developed countries trysurvive by cutting costs, modernizing production processes, (flexible, reprogramable andlean production systems) and developing innovative products constantly refreshed andmanufactured in small quantities with daily orders quickly sent to the points of sales.This implies tremendous efforts, both technical and financial, permanent alterations inproduction processes, accurate and timely information on market and on consumerstrends, strong relations with suppliers of high quality materials and components, andgreat ability to meet costumer needs promptly.

For a company producing 1000 pairs a day, the production of more than 500 newmodels per year, the preparation of 4 season collections, the simultaneousmanufacturing of more than 10 different models per day are usual.

The manufacturing companies in developed countries, without the appropriate capacityand resources to adopt an innovative and aggressive commercial strategy, try surviveacting as sub-contracted concentrated in the manufacturing operations.

The sourcing of finished footwear of the commercial and distribution companies, or ofthe retailers and shops, does not favour the position of the SME producing footwear inoutside the low cost Asian Countries:

The companies dominant in commercial and distribution have their own brandsand assume almost totally the functions of branding, marketing, productdevelopment and purchasing of materials and components, subcontracting theproduction, total or partially.

Their big orders are subcontracted, total or partially, at cheap labour countries. Thesmall orders placed in the neighbour countries are many times a problem with lowprofit, caused by price reduction, increased administrative costs, with faster

deliveries, new tasks in labelling and improved quality without price increase; etc; The small retailers and independent shops place to footwear companies other

challenges demanding them innovative products, immediate and irregulardeliveries following the seasonality of the consumption, long stated periods ofpayment conditioned by sales.

As a result of these strategies, the European SME work with a great variation of modelsand small orders requiring new tools and programs or manual processes, as the cuttingof leather.

To survive the SMEs in developed countries tend to adopt advanced methods ofmanagement accomplished with the use of production technologies, workplace

organization, supervising, training, product design and product engineering, productionplanning, costumer relations management, etc all of them with the objectives to improveoverall business activity:


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Reduce the production cycle time Reduce the work in process

Increase flexibility and quick response deliveries Reduce administrative and indirect costs

Reduce the dependence on high skilled operators (with modern technologies) Increase the level of customer service

2. Available technologies

Technologists tend to act as if modern technology is the solution for any problem. Thisway of thinking can deviate the attention from the real and decisive factors affecting theproductivity and competitively of companies. It will be always remembered that are 3categories of equipments:

Equipments that all shoe manufacturing unities must use; Equipments that only the most updated shoe manufacturing unities can use;

Equipments that some manufacturers say they are using only for giving a modernimage.

Equipments and technologies are tools to increase productivity and competitiveness andnot an objective in itself.

Some of the top quality and fashionable shoes are made by hand or with traditionalmachines and massive shoes can also be produced in sophisticated and modernmanufacturing lines.

But in a general way technology if correctly used is of great value for the profitability ofmanufacturers.

Matching and integrating technologies and equipment of diverse suppliers it is possibleto envisage a footwear company with an high automation level, (figure 1).

Figure 1: Available technologies to footwear industry


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Technical level of equipments

The technical level of equipments is not the only factor that favours their utilization. Theexistence of maintenance and technical assistance is so important that some equipmenthas a great utilization in one manufacturing area and can be unknown in another area.This occurs with the injection machines or with CAD/CAE/CAM systems.

The technical value of a technology or equipment is not the key factor for theiracquisition, but the economical one. For instance the cutting of moccasin uppers withstitching holes can be technically perfect with a cutting press and special cutting dies,but is only economically advantageous for orders above a certain amount per size. Thesame is valid for automatic stitching.

The investments in the technology can deviate the company focus of other equallyimportant areas, as reducing the waste of materials and components, which count forabout the 40-50% of the cost of a shoe.

The technological innovations at footwear companies registered a significant andbeneficial evolution in the recent years with improved productivity, reduction of the

labour content, reduction of the required operators skills, more consistent quality, betteruse of materials.

Limitations to the increase of the automation and the technological up-grade also exist:

The reduction in labour costs can not be compensating, The strategy of the commercialisation and distribution companies favours the

production moving more than automation, The high cost of the technologies and the qualified requirement of technicians to

program them, does not favour its acquisition by SME - small e medianenterprises.

Integration level

Another important aspect in the use of technologies is the level of integrationrecommended, varying from the using of individual machines without any specialintegration or transfer of information, or by the implementation of islands of automationin automatic stitching, leather cutting, lasting processes; roughing, applying of adhesive,drying and reactivation, etc. just to the implementation of automatic production lines withrobots.

The implementation of high levels of integration needs specialized human resources.The training of skilled operators can be problematic and cost a great percentage of thetechnology costs before its full utilization.

The technologies with more impact in the production sections, excluding the solutionsfor the areas of the planning and management, design and engineering (CAD/CAEsystems), marketing, quality, are showed in table 2

Table 2: Technologies for production sectionsTechnological Area System/Equipment

Logistic Material and component warehouses (stored in boxes,paletes, boards, etc.)

Warehouses for finished shoes( in boxes, cartons, pallets,etc.)

Work in progress warehouses (normally over the production

lines) Systems for dispatching and/or automatic reception of

materials, components and finished products


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Production management Production balancing and simulation systems Shop Floor control systems l

Cutting Automatic cutting systems: by knife, water jet, laser Press with cutting dies

Stitching Stitching machines with productivity devices like underbedthread trimming, needle positioning,

Computer controlled stitching machines with pallets. Assembly Lasting conveyors integrating heat oven, freezers, etc.

Automatic: machines for toe, seat and side lasting, to applyadhesives,

Machines with robot: to side and bottom upper roughing,apply adhesive,

Integrated lines for injection and cemented shoes.

Considering the currently available technologies it is possible systemise some islands ofautomation, for grouped operations (table 3).

Table 3: Islands of automationIsland of

automationManufacturing

operationsAdvantages / disadvantages

Patternengineering

Design Pattern development and scale

Tooling design and sampleprototyping

Programming CNC machines PDM

Model costing

Rigour Rationalization of tools and

model engineering Increased administrative and

technical tasks Need of technicians with new

qualification

High level of investment

Prototyping oflasts, cutting dies,sole moulds

Design and engineering

Sample prototyping CNC files for milling machines

Rigour

Rationalization of tools

Increased complexity

Need of technicians with newqualification

High level of investmentLogistic Reception, storage and

distributing of materials andcomponents

Linking and transfer between

machines and productionsections

Work in progress storagesystem

Reducing of labour content(50-70%)

Beter retrieval andmanagement of data

Increased administrative andtechnical tasks

Need of technicians with newqualification

High level of investmentAutomatic cutting Semi-automatic grading of

leathers Leather measuring (total and by

quality areas)

Automatic nesting (cut plans) Cutting

Production control

Semi-automatic grading ofleathers and classification ofsuppliers

Reducing of labour content(20-30%)

Elimination of cutting dies

Gain of leather (5-10%) Increased administrative and

technical tasks


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High level of investmentAutomaticStitching

Design and production of pallets Programming of stitching

machines

Junction and stitching of severalpieces

Reducing of labour contentwith automatic machines (30-50%)

Reducing of labour contentwith stitching devices attraditional machines (12-20%)

Cost of pallets (economicalviability to quantities above5000 pairs per pallet)

InvestmentAssembly Humidification of uppers

Toe lasting Seat and side lasting Heat last stabilization

Reducing of complexity andlabour content (20-30%)

Increased productivity andflexibility

Increased quality

Investment

Cementing andsurfacepreparation

Chemical halogenation of soles Mechanical roughing of uppers Applying of adhesive Drying Reactivation

Press

Reducing of complexity andlabour content

Increased productivity Reduction of adhesive

consumption

Time of programming (in caseof robots)

InvestmentDirect injection/vulcanisation

Application of release agent Roughing of uppers

Application of adhesive Injection Last removal

Sole trimming

Shoe finish

Reducing of complexity andlabour content

Increased productivity

Time of programming (in caseof robots)

High investment High cost of molds Economical viability only to big

orders High commercial risk


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3. Overview of footwear technologies

3.1. The Management systems

Typically the global cycle production time of a fashion shoe can be about 40 minutes perpair. But the permanence at factory can take more than 4 days, i.e. less than 2%. Thesenon-productive and non-added value operations cost money and occupy productionresources.

The utilisation of efficient production planning and controlling systems can manage theexcessive work levels that SMEs have nowadays with the production of small orders,the deliveries to different point of sales, the sourcing of raw materials, components andaccessories from different suppliers, etc.

The implementation of such a system with a lean production philosophy can:

Reduce the production cycle time by 75% Reduce work in progress by 75%

Increase productivity by 10-15% Reduce manufacturing space by 25% Reduce quality faults by 50%

The production of small orders and even only one pair needs that every one iscommitted with quality. Total quality management systems according ISO 9000 standardcan assure the required quality.

3.2. The Logistic systemsThe logistic operations inside the companies are assuming an increased complexity as aresult of the:

High number of different models in production,

High number of materials and components used in every shoe, External subcontracting of shoe uppers,

Inputs and outputs to and from warehouses, Diversity of the work in progress in manufacturing lines,

Distribution of materials between working posts Dispatching of shoes in small quantities for different and numerous points of sale.

The labour costs of persons involved on the logistic operations are increasing andactually they can represent about 10% of the salaries. The complexity of the operationsis equally a source for manufacturing faults and productivity problems.

The work in process can represent also several times the daily production. On well-organized factories, manufacturing the entire shoe by the cemented method, 5 days ofwork in process is adequate. High figures can be a signal of inefficiency. But wheresubcontracting occurs extra work in progress is required.

The footwear industry can use adequate technical solutions for the storage, distribuitioninto production and delivering operations (figures 2-5), allowing:

A significant reduction of labour on materials reception, materials distributionbetween sections and machines, expedition to other stores, etc,


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Better information on existences, orders, lack of materials, delay on provisions,productivity analysis.

Figure 2: Automatic warehouse for raw-materials and components

Figure 3: Automatic warehouse work in progress (over the productive lines)

Figure 4: Automatic stitching conveyor

Figure 5: Automatic conveyor for assembly lines


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The software of logistic applications provide a wide range of real time information: Input and output of the materials, components and finished shoes,

Storage time of each material, Productivity per operator,

Materials needs and availabilities per order, models and for defined periods, Stock management of the row materials and components,

Management of subcontracted components, Balancing of the productive operations and neck points previsions,

Management of materials and components supply ruptures

3.3 The cutting technologies

The cutting organization

A relevant aspect of the cutting process is that the cost of material is several times

higher than the labour cost. Even in high labour cost countries the value of leather is atleast ten times the corresponding labour cost. In low labour countries this ratio is farhigher. So the most important is to cut with the minimum of material wastage.

More important than the technology and equipment used is a correct processorganization for:

Designing the models correctly with adequate size and good interlocking ofpieces, limited stitching and lasting margins;

Engineering of models using standard patterns for more than one style;

Measuring and classification of leather supplies, Controlling the amount of leather sent to cutters;

Controlling the amount of leather received from the cutters Inspecting the quality of cut pieces

Adequate training is fundamental for cutting workers. The selection of the bestinterlocking of the press knives, the necessity of considering the directional and qualityconstraints are key competences of cutters. The production and material utilisation givevariable results from each cutter.

Experience shows that differences in leather saving can vary between 5-10%

Measuring and grading of leather

An automatic system like the DigiLeather (Fig. 6) can measure automatically the globalarea of a leather, the useful area (without defects) and the sum of the areas with defectsof level 1, level 2, level 3 and so on.


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Figure 6. Automatic leather measuring and grading

The same system can be used to measure the amount of leather returned to

warehouse.Measuring the area of leathers supplied by tanneries against the area indicated andmarked on leathers, gives in general differences not less than 2%.

Press cutting

The cutting by press with cutting dies (press knives) is the most common cuttingmethod. It is an inexpressive cost operation for massive manufacturing. The swing armpress is mainly used in leather upper cutting. The travelling head press or the beampress are more favourable because can be used for leather cutting in single layer or forsynthetic cutting in multi layer.

Considering the number of sizes (8 to 10), the number of components per style and thewidth fittings the required number of knives can reach 250.

The press knives have frequently accessories like prickers and punch tubes for stitchmarking and moccasin holes.

The search, storage and maintenance can be a little complex in great factories. Theutilization of special armoires for press knives can reduce that.

The travelling head press can be almost automated. Computer controlled travelling headpress although more expensive are mainly used in cutting synthetic materials inmultiplayer: its higher output (3 to 5 times more), automatic lay planning with material

gain of 5-15 % and quality consistency make them specially indicated for insole, toepuffs, heel stiffeners, soles (from sheet materials). These machines are equipped withmaterial feed systems.


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Automatic cutting

The cutting with press knives is the most common method. But for small orders the costof cutting knives become economically incompatible. In this case the hand cutting or theautomatic cutting systems are the remaining solutions.

The automatic cutting systems needs no cutting dies and gives a quick response to

production demands.There are several types of automatic systems.

In the simpler one also called projection cutter, model pieces are projected over leatherin a visual lay planning. These systems with one or two stations are suitable for sampleand small orders cutting. The output is about 130 to 170 pairs/day for knife cuttingsystem (fig 7), and just to 400 pairs/day with water jet 2 stations systems (fig.8).

Figure 7: Knife cutting system. Figure 8. Water jet cutting system

Stitch and size marking and punching can be done in these automatic systemsdecreasing the production output. Recent development includes machines for executingthese operations in cut pieces by laser or automatic punching.The cost of cutting dies isreduced in press cutting machine or the production output is increased in automaticsystems.

There are also integral cutting systems (fig. 9) composed by: A digitizing system using video captures of the contours of leather and semi

automatic taking of the position and quality of leather faults.

A inject marking system A nesting program for automatic lay planning

A water jet cutting table with high production (1000 pair/day)


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Fig. 9.Integrated cutting system

A similar approach exists for the cutting of synthetic materials in rolls or sheets.

In next table the strengths and weaknesses of several cutting systems are summarised.

Cuttingprocess

Process strengths Process weakness

Hand cutting No capital outlay

Low tooling cost: cardboards patterns

Reduced tooling time (some hours)

Labour intensive

Requires high operator skills

Low production rate: 60-70pairs/day/worker

Only adequate for small orders and

samples with quickly demands

Press cuttingwith cutting

knives

Low cost operation on big orders Low to medium production rate (200-

300 pairs/day/worker)

Low maintenance and acquisition

equipment cost

The cost of cutting dieseconomically unviable for smallorders (


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3.4 The stitching operations

The labour content of stitching and pre-stitching operations represents about 50% of thewhole production labour. Any profit or loose in these sections has impact at the yieldlevel of the company.

The use of conventional modern stitching machines under bed thread trimming, needlepositioning, automatic thread cutters, variable speed motors, etc can increase theoperators productivity of around 30% over older ones.

The use CNC stitching machines also allows considerable profits in productivity, andparticularly in very complex models. Also the use of palettes composed by severalsheets allows the grouping of operations, reducing in such a way the number ofoperators involved.

However, the high cost of palettes and high time of programming, make this process aviable solution only for orders over 5.000-10.000 pairs per pallet.

But once more, some factors besides the technology and machines will affect greatly theproductivity of factories:

Bad designed and engineered models with complex stitching curves, inexistenceof stitching marks or appointing lines,

Unnecessary extra operations. Bad distribution of work in progress among operatives, with excess of moving,

standing up and sitting down, Bad balance among workers.

For small stitching sections, with production capacities that do not exceed the 300-500uppers/day the work organization in cells or rings with polyvalence and technical

qualification of the operators is mostly adequate (fig. 10).

Fig. 10: Work cells in a stitching line

The sophisticated equipment and technologies are in many cases inadequate

For stitching lines with 40 or more operators the use of distribution systems like thefeeder operator feeder conveyor for small and variable series, or the feeder operatoroperator conveyor for long short series, are recommended. (fig.11).


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Fig. 11: Automatic stitching conveyor

A new generation of conveyors with software applications:

Rules the sending of working boxes for the adequate working posts according thecapabilities of operator, thread colour, priorities of shoes

Control and monitor the operator productivity, the time per model or per order, thesample production,

Define urgencies and priorities (for repaired or damaged shoes, for completingdeliveries, etc).

Gives alarms on excessive working time for each operator.

With large stitching lines with more than 50-60 workers the use of automatic conveyors

linked to automatic storage and distribution system of work in progress is the mostsuitable solution. (fig. 12)

Fig. 12: Automatic stitching conveyor with box warehouse

3.5 Assembly and Finishing

A traditional assembly line with 8 workers can last about 1000 pairs/8 hours of cementedshoes.


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Actually the assembly equipments incorporate already a high level of automation makinguse of microprocessors, which reduces significantly the set-up time of the machines andthe change of programmes. It is the case of toe lasting machine, seat and waistmachine, automatic roughing or cementing machines. These equipments have reducedthe complexity of assembly operations and are responsible for high gains of productivity.

The substitution of some automated equipments by systems mounted in robots, namelyfor roughing operations, adhesive application, handling work in progress betweenmachines have great impact on productivity.

However the implementation of integrated robot lines for assembling shoes (figure 12),using a reduced number of persons will be a possibility solution for bigger companiesdue to huge investment.

Integrated and robotized assembly lines needs high qualified technicians in software,electronics, machine programming, tooling for machines. Programming is complex andtime costly and so recommended for medium and big series.

Figure 13: robot equipments in assembly line

4. Strength and weakness of automation

The investment on automation will be, on a medium and long time, necessary to reduce:

The workforce involvement especially at the non added value operations, such ashandling and controlling materials or products;

The complexity of the operations improving a coherent quality and conformity withstandards, in operation like lateral roughing.

If experience shows that technological obsolete companies will not survive, it is notuncommon the difficulties of some firms who invested highly in advanced technologies.

The implementation of new technologies usually will demand:

New operators with new skills (mechanics, computers and software, electronics,etc)

Additional technical and administrative tasks for supporting the new processes,inexistent on former traditional ones (e.g. materials codification, operativeinstructions, , linkage and files transfer between others systems, etc);


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Additional tasks for programming equipments, definition of quality conditions(temperatures, pressings, times, etc);

Additional tasks on collecting and data management information operations;

Higher quality demands of product engineering processes, increasing the costswith knives, moulds, lasts, etc, when using the automation processes;

Higher functioning and maintenance costs which are almost inexistent in the

traditional plants.

In such a way, automation can be responsible for an increase of administrative labour,depreciation and dissatisfaction on the company staff as well as the increase of conflictsbetween the new technicians and supervisors involved in the new technologies and theold staff.

Is then essential that the Management Board elaborates a modernization planpreviewing training and motivation actions for their staff.

The implementation of an advanced integrated line is much more complex, anddemands the simultaneous availability of several technicians with different qualifications,

with priority over all other functions. The inexistence of these persons condemns theinvestment to failure in a majority of cases.

Therefore, the implementation of modern and complex technologies follows almostalways a model of automation step by step, from one section to another:

Cutting processes;

Warehouses for raw materials and components; Warehouses of finished products;

Automation of the lasting operations Automation of the bonding operations: roughing, adhesive application,

reactivation, press of upper and sole;

Automation of stitching distributing (conveyor) Automation of the assembly conveyor.

Can the implementation of a new technological organization strengthens the advantagesof SMEs in developed countries and prevent the moving of the production sites to cheaplabour countries?

Two alternatives are pointed currently solve this question:

The agile production systems, including the implementation of flexibleproduction lines from the design and engineering phases to cutting, stitching,assembly and finishing, specially developed for the production of individualizedshoes.

Segmentation of a shoe in engineered components, each of them manufacturedin a full automated production line, assembled together in the footwear company,in a process similar to the automobile industry

The agile production systems requires the existence of advanced and flexibleequipments with reduced set-up times, auto adjustable, essentially customized to theproduction of small series.

In the assembly model, the strategy of segmenting the footwear production inindependent components is strengthened. Through one rigorous design the footwear isdeveloped as being constituted of a set of components produced in the external smallunits, with high automation level, operating 24 over 24 hours.


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The design and cut of leathers, equipped with high-speed cutting systems, are alreadyin functioning. The same is true for soles, insoles and other bottom components. Thenext step will be probably stitching.

In my opinion the delocalisation cannot be stopped, but a more significant portion offootwear production can remain in those countries

J. Leandro de Melo

Managing Director

Centro Tecnolgico do Calado

Portugal

September, 2003.

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