APPAREL GARMENTS PRODUCTION SYSTEMS

Apparel Garments production is the last process of textile production. Garments production is the heart of textile production. Garments production includes the production of production of finished apparel garments. An apparel garments production system is an integration of materials handling, production processes, personnel, and equipment that directs work flow and generates finished garments products. Three types of production systems commonly used to mass produce apparel are: progressive bundle production, unit production, and modular production of garments.

Each system of garments production requires an appropriate management philosophy, materials handling methods, floor layout for garments spreading, and employee training. Firms may combine or adapt these systems to meet their specific garments production needs. Firms may use only one production system, a combination of systems for one product line, or different systems for different product lines in the same plant.

Objectives of garments production system:

 -Examine the characteristics of different types of apparel production systems

 -Compare and contrast the different production systems

 -Evaluate and critically compare the use of systems in different contexts

 -Summarize the benefits of the different garments production systems

 Progressive Bundle Production System of garments manufacturing:

The progressive bundle system (PBS) of garments production gets its name from the bundles of garment parts that are moved sequentially from operation to operation. This system, often referred to as the traditional garments production system, has been widely used by garments manufacturers for several decades and still is today. The AAMA Technical Advisory Committee (1993) reported that 80 percent of the apparel manufacturers used the bundle system of garments production. They also predicted that use of bundle systems for garments production would decrease as firms seek more flexibility in their production systems.

Bundles system of garments production consist of garment parts needed to complete a specific operation or garment component. For example, an operation bundle for pocket setting might include shirt fronts and pockets that are to be attached with garments. Bundle sizes may range from two to a hundred parts. Some firms operate with a standard bundle size of particular garments, while other firms vary bundle sizes according to cutting orders, fabric shading, size of the pieces in the bundle, and the operation that is to be completed. Some firms use a dozen or multiples of a dozen of garments because their sales are in dozens. Bundles of garments are assembled in the cutting room where cut parts are matched up with corresponding parts and bundle tickets.

Bundles of cut parts are transported to the sewing room in the garments and given to the garments operator scheduled to complete the garments production operation. One garments operator is expected to perform the same operation on all the pieces in the bundle, retie the bundle, process coupon, and set it aside until it is picked up and moved to the next operation of garments production. A progressive bundle system of garments production may require a high volume of work in process cause of the number of units in the bundles and the large buffer of backup that is needed to ensure a continuous work flow for all operators in garments.

The progressive bundle system of garments production may be used with a skill center or line layout depending on the order that bundles are advanced through garments production. Each style may have different processing requirements and thus different routing. Routing identifies the basic operations, sequence of garments production, and the skill centers where those garments operations are to be performed. Some garments operations are common to many styles, and at those operations, work may build up waiting to be processed.

Disadvantages of progressive bundle system of garments production:

The progressive bundle system of garments production is driven by cost efficiency for individual garments operations. Garments operators perform the same operation on a continuing basis, which allows them to increase their speed and productivity. Operators of garments who are compensated by piece rates become extremely efficient at one garments operation and may not be willing to learn a new garments operation because it reduces their efficiency and earnings. Individual operators that work in a progressive bundle system of garments production are independent of other operators and the final product.

Slow processing, absenteeism, and equipment failure may also cause major bottlenecks within the system. Large quantities of work in process are often characteristic of this type of garments production system. This may lead to longer throughput time, poor quality concealed by bundles of garments, large inventory, extra handling, and difficulty in controlling inventory of garments industry.

Advantages progressive bundle system of garments production:

The success of a bundle production system of garments manufacturing may depend on how the production system is set up and used in a plant. This production system may allow better utilization of specialized garments production machines, as output from one special purpose automated garments machine may be able to supply several garments machine operators for the next operation. Small bundles of garments allow faster throughput unless there are bottlenecks and extensive waiting between operations.

Unit Production System of garments manufacturing:

A unit production system (UPS) of garments production is a type of line layout that uses an overhead transporter system to move garment components from work station to work station for assembly. All the parts for a single garment are advanced through the production line together by means of a hanging carrier that travels along an overhead conveyor. The overhead rail garments production system consists of the main conveyor and accumulating rails for each work station of garments. The overhead conveyor operates much like a railroad track. Carriers are moved along the main conveyor and switched to an accumulating rail at the work station where an operation is to be performed. At the completion of an operation the operator presses a button, and the carrier moves on to the next operation.

Most unit production systems of garments production are linked to a computer control center that routes and tracks production and provides up-to-the-minute data for management decisions. The automatic control of work flow sorts work, balances the line, and reduces claims of favoritism in bundle distribution in garments production. Electronic data collection provides payroll and inventory data, immediate tracking of styles, and costing and performance data for prompt decisions.

Processing begins at a staging area in the sewing room of garments. Cut parts for one unit of a single style are grouped and loaded directly from the staging area to a hanging carrier. Loading is carefully planned so minimal handling is required to deliver garment parts in precisely the order and manner that they will be sewn. When possible, garments operations are completed without removing the parts from the carrier. Varied sizes and types of hanging carriers are available for different types of garments products. Automated garments handling replaces the traditional garments production system of bundling, tying and untying, and manually moving garment parts. Unit production systems eliminate most of the lifting and turning needed to handle bundles and garment parts.

The need for bundle tickets and processing operator coupons is also eliminated when an integrated computer system monitors the work of each garments operator. Individual bar codes or electronic devices are embedded in the carriers and read by a bar code scanner at each workstation and control points in garments factory. Any data that are needed for sorting and processing such as style number, color shade, and lot can be included.

Integrated garments production systems have on-line terminals located at each work station to collect data on each operation. Each garment operator may advance completed units, reroute units that need repair or processing to a different station of garments, and check their efficiencies and earnings. Garments operator may signal for more inventory or call for a supervisor if assistance is needed. The terminals at each station enables central control center to track each unit at any given moment and provide garments management with data to make immediate decisions on routing and scheduling.

Garments operators of the UPS control center can determine sequences of orders and colors to keep operators supplied with work and to minimize change in equipment, operations, and thread colors. A unit garments production system can control multiple routes and simultaneous production of multiple styles without restructuring production lines in garments. The control center may perform routing and automatic balancing of work flow, which reduces bottlenecks and work stoppages. Each operator as well as the control center is able to monitor individual work history. Data can be collected on the amount of time an garments operator works, time spent on each individual unit, number of units completed, the operator who worked on each unit, and the piece rate earned for each unit in garments. The system of garments production will calculate the earnings per hour, per day, and the efficiency rate of each garments operator.

Advantages of Unit Production System of garments production:

Benefits of a unit garments production system depend on how a production system is used and the effectiveness of management. Throughput time in the sewing room can be drastically reduced when compared to the progressive bundle system of garments production because works in process levels are reduced. Garments operator productivity increases. Direct labor costs are reduced because of prepositioned parts in the carriers and elimination of bundle processing. Indirect labor costs may be reduced by elimination of bundle handling and requiring fewer supervisors. Quality is improved because of accountability of all garments operators and immediate visibility of problems that are no longer concealed in bundles for extended periods of time. The central control system in garments production makes it possible to immediately track a quality problem to the operator that completed the operation. Other benefits that are realized are improved attendance and employee turnover and reduced space utilization.

Disadvantages Unit Production System of garments production:

Considerations for installing a UPS include costs of buying equipment, cost of installing, specialized training for the production system, and prevention of downtime. Down time is a potential problem with any of the garments production systems, but the low work in process that is maintained makes UPS especially vulnerable.

Modular Garments Production System

A modular garments production system is a contained, manageable work unit that includes an empowered work team, equipment, and work to be executed. Modules frequently operate as mini factories with teams responsible for group goals and self-management. The number of teams in a plant varies with the size and needs of the firm and product line in garments. Teams can have a niche function as long as there are orders for that type of garments product, but the success of this type of garments operation is in the flexibility of being able to produce a wide variety of products in small quantities in garments.

Many different names are currently used to identify modular garments production systems, including modular garments manufacturing, cellular garments manufacturing units, compact work teams, flexible work groups, self-directed work teams, and Toyota Sewing System (TSS) in garments. The basic premise is similar among these production systems, although the organization and implementation may vary.

The number of employees on a team, usually 4 to 15, varies with the product mix. A general rule of thumb is to determine the average number of operations required for a style being produced and divide by three. Team members cross-trained and interchangeable among tasks within the group. Incentive compensation is based on group pay and bonuses for meeting team goals for output and quality. Individual incentive compensation is not appropriate for team-based garments production. Teams may be used to perform all the operations or a certain portion of the assembly operations depending on the organization of the module and processes required. Before a firm can establish a modular production system, it must prioritize its goals and make decisions that reflect the needs of the firm.

With a team-based system operators are given the responsibility for operating their module to meet goals for throughput and quality. The team is responsible for maintaining a smooth work flow, meeting production goals, maintaining a specified quality level, and handling motivational support for the team. Team members develop an interdependency to improve the process and accomplish their goals. Interdependency is the relationship among team members that utilizes everyone's strengths for the betterment of the team.

Work flow in modular garments production

A Modular garments Production System operates as a Pull System, with demand for work coming from the next operator in line to process the garment. Wastage is normal, and workflow is continuous and does not wait ahead of each operation. This increases the potentials for flexibility of styles and quantities of products that can be produced. Teams usually operate as ‘Stand-up’ or ‘Sit-down’ units.

A module may be divided into several work zones based on the sequence of garments operations and the time required for each operation. A work zone consists of a group of sequential garment operations. Operators are trained to perform the operations in their work zone and adjacent operations in adjoining work zones so they can move freely from one operation to another as the garment progresses.

Work flow within a module may be with a Single-piece hand-off, Kanban, or Bump-back system. If a single-piece hand-off is used, machines are arranged in a very tight configuration. As soon as an operation is completed the part is handed to the next operator for processing. Operations need to be well balanced as there is usually only one garment component between each operation. Some modules may operate with a buffer or small bundle of up to ten pieces of work between operators. If a small bundle is used, an operator will complete the operation on the entire bundle and carry the bundle to the next operation. An operator may follow a component or bundle for as many operations as they have been trained or until the adjacent operator is ready to assume work on the bundle.

A Kanban uses a designated work space between operations to balance supply with demand. The designated space will hold a limited number of completed components (two or three) in queue for the next operation. If the designated space is full, there is no need to produce more until it is needed or the space empties. These limits build up of product ahead of the next operation. When the space is full the operator can assist with other operations that may be slow.

The bump-back or TSS (Toyota Sewing System) approach was developed by the Toyota Sewn Product Management System and is probably the most widely used type of team-based manufacturing. It is a stand-up module with flexible work zones and cross-trained operators. Operators may be cross-trained on up to four different successive operations. This enables operators to shift from operation to operation until the next operator is ready to begin work on the garment. The operator needing work steps to the beginning of the zone and takes over the processing at whatever point it is in the production process. The operator who has been relieved of the garment will then move back to the beginning of the work zone and take over work on another garment. This approach enables continuous work on a garment and allows each operator to perform several different operations. This arrangement frequently uses a 4-to-l ratio of machines to operators.

Advantages of a Modular Garment Production System are:

1.) High flexibility

2.) Fast throughput times

3.) Low wastages

4.) Reduced Absenteeism

5.) Reduced Repetitive Motion Ailments

6.) Increased employee ownership of the production process

7.) Empowered employees

8.) Improved Quality

Disadvantages of Modular Garments Production System:

1.) A high capital investment in equipment.

2.) High investment in initial training.

3.) High cost incurred in continued training

Combinations of Garments Production Systems

Some firms may use the progressive bundle system for producing small parts combined with modular production for garment assembly. This reduces the investment in specialized equipment and reduces the team size needed. Some industry consultants believe that a modular system combined with a unit production system provides the most flexibility, fastest throughput, and most consistent quality. This would be particularly useful for large items such as coveralls or heavy coats. The UPS would move the garment instead of the operators. Each manufacturer needs to determine what is best for its product line and production requirements.

GARMENTS PRODUCTION PROCESSES OF APPAREL FACTORY

Objectives of garments production process:

  -Examine garments production strategies and concepts

  -Explore the relationship among production standards, capacity, and production planning

  -Examine factors that impact productivity and measures of productivity.

The plant and production system create the environment for executing production processes. A process is a procedure required to convert materials into a specific product or style. The type and sequence of garments production processes required for conversion is unique to each style. Use of inputs to the process (including materials, methods, machines, and skills) is determined by the expected output.

Process Analysis and Control:

Process analysis begins with examination of each style to determine its requirements for production. Style requirements are discussed at product planning meetings, determined through analysis of samples and specifications, and evaluated based on a firm’s standard operating procedures and cost constraints. Production skills, production time, equipment needed, and the anticipated volume are evaluated for each style.

The basic breakdown of operations for a style is often identified by technical designers while engineers develop detailed specifications, methods, and production standards necessary for consistently executing the processes. An operation is one of the steps in a process that must be completed to convert materials into a finished garment. An operation breakdown is a sequential list of all the operations involved in cutting, sewing, and finishing a garment, component or style.

Production Standards:

Production Standards are a means of controlling time and labor costs by establishing a reasonable time for completing each operation. They provide a basis for determining whether the actual production time and costs are acceptable. Production standards are used to plan and schedule production, analyze capacity, and serve as performance criteria for workers. Production standards provide management with a numerical base (quantitative base) for making decisions and managing plant production. A production standard reflects the ‘Normal’ time required to complete one operation or cycle using a specified method that will provide the expected quality. In comparing actual performance with a production standard, trouble spots can be identified, productivity evaluated, and adjustments can be made.

Labor Efficiency for production development:

Labor efficiency is ratio of work accomplished versus the work expected to be accomplished. The work accomplished is provided by the operator’s output sheet and the work expected to be accomplished is provided by the production standard.

Labor Performance in production field:

Combining labor efficiency with labor utilization provides the basis for the labor performance report. Labor performance can be loosely translated as labor productivity

GARMENTS SEWING MACHINE FUNDAMENTALS- PRINCIPLES OF STITCHING (MECHANIZATION PROCSS)

Sewing machine is an important part of apparel and garments manufacturing technology. Production of garments factory depends on the performance of sewing machine and principles of stitching. Principles of stitching and perfection of stitching depends on the quality of sewing machine.

Mechanization is the process of replacing human labor with machines. Mechanization of the garments sewing process encouraged mass production of apparel garments product. Garments sewing that had long been performed by hand sewing machine could be done more rapidly by garments sewing machine. By about 1900, most garments sewing processes could be performed by machine

Automation is a state of operating without external influence or control. In manufacturing of garments and apparels it is often viewed as highly desirable because it eliminates the potential for garments workers error. Automated garments sewing systems are capable of feeding themselves cut garments parts from a stack, completing multiple sewing tasks, and delivering finished parts of garments. Automated equipment for garments sewing may be cost effective for some apparel manufacturers, while the high costs of acquisition, installation, and maintenance are prohibitive to others.

Robotics is the most advanced form of automation in garments sewing operation. Robots are computerized, reprogrammable, multifunctional manipulators designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks. Flexible reprogramability is one of the hallmarks of robotic automation. This manufacturing flexibility differentiates robotics from fixed-purpose, hard-wired automation, which has to be torn apart and reconfigured for every new application.

Garments sewing and Apparel pressing equipment may be either general or special-purpose. General-purpose garments sewing machines are manually operated by garments worker and can perform a variety of sewing operations. Special-purpose garments sewing machines are designed to perform a specific garments related or sewing related operation and more likely to be semiautomatic or automatic machine.

Objectives of garments sewing machine:

 -Discuss issues related to equipment selection

 -Explain mechanization and automation relative to special- and general-purpose garments sewing machines

 -Examine the basic components of garments sewing machines and work aids

GARMENTS SEWING MACHINE FUNDAMENTALS:

A basic garments sewing machine or apparel sewing head, as it is sometimes called, consists of the fundamental parts required to form a stitch, sew a seam, or perform a specific garments sewing operation. The major components of a basic garments sewing machine include a sewing casting, a machine lubrication system, a stitch-forming system, and a garments feed system. The speed at which a sewing machine can operate depends on the engineering of the garments machine’s components.

The Sewing Casting:

The sewing machine casting is the metal form that provides the exterior shape of the garments machine. Shapes vary with the bed type, the garments sewing function that is to be performed, and how piece goods are to be presented to the needle. The casting houses the internal workings, such as the gears, cams and shafts, that operate the stitching and feeding mechanisms of the sewing machine.

Bed Type:

The bed is the lower portion of the sewing machine under which the feed mechanisms and loopers are located. Sewing machines are frequently described by bed types.

Different Types of Machine Beds:

Types of Garments Sewing Machine       Sewing

Stitch Type          Features and Uses

Flat bed sewing machine (basis type)     Lockstitch sewing, Chain stitch sewing    The large working area allows a wide range of sewing application; the material can easily be guided around the needle and the presser foot. This basic type garments sewing machine used for all kinds of flat sewing operation.

Raised bed sewing machine        Lockstitch sewing, Chain stitch sewing    The bedplate is in the form of a plinth. It facilitates the assembly of pre-sewn parts and is especially suitable for the fitting of accessories and special attachments. This is the basic form for various specialized garments sewing machines such as buttonholers.

Post bed sewing machine            Lockstitch sewing, Chain stitch sewing    This type of sewing machine has an increased working height. Special sewing applications are found in the working of three-dimensional products. e.g. shoes and bags. The post makes it easier to work on tight curves and corners, to sew in sleeves and to complete large, half-assembled products.

Cylinder bed sewing machine     Lockstitch, Chain stitch This type of garments sewing machine has an increased working height and a bed in the shape of a horizontal arm. It is especially suitable for sewing on tubular parts, such as cuffs, sleeves, and trouser legs, and also for button sewing and bar tacking.

This sewing machine is used extensively in the making of clothing from knitted fabrics.

Side bed machine            Chain stitch, Over-edge                Machines which are specialized for sewing at edges need only a small working area

THE LOCKSTITCH MACHINE; GARMENTS SEWING MACHINE USED MOST OF THE APPAREL FACTORY

Lockstitch sewing machine is very popular sewing machine and widely used in most of the conventional modern garments sewing system. The lockstitch machine is very easy to use but required more power to operate.

Principal feature and sewing elements of a flat-bed lockstitch sewing machine

The three-thread overlock sewing machine

Objectives of lockstitch sewing machine:

-Explain mechanization and automation relative to general- and special-purpose machines

-Examine the basic components of sewing machines and work aids

-Discuss the effect of equipment on product quality and performance

Modern mass-production sewing requirements have resulted in many variations of the basic flat-bed lockstitch sewing machine. As we have seen, many of these developments are concerned with the form of the bed on which the material to be sewn rests. Cylinder-beds, post-beds, raised- and feed-off-the-arm beds have given rise to machines which differ greatly in appearance, although the actual stitch forming elements contained in these machines remain basically the same. These mechanisms may be grouped under one or other of the two main headings, Rotary hook or Oscillating Shuttle.

The principal features and sewing elements of a modern flat-bed lockstitch machine of the rotary hook type are as illustrated in the figure given below:

Principal feature and sewing elements of a flat-bed lockstitch machine

The primary components concerned with the formation of the stitch are:

(i) The needle,

(ii) The feed dogs,

(iii) Throat plate,

(iv)The presser foot,

(v) The rotary sewing hook, and

(vi)  Bobbin and the bobbin case.

Each of these components is a precision product and for its proper functioning must be in perfect condition, with their positions accurately set and, in the case of moving parts, perfectly timed in relation to the movement of the other components.

Stitch forming action of the rotary-hook lock stitch machine:

Rotary-hook machine forms the plain stitch or simple two thread lock stitch by carrying the needle thread loop around a bobbin containing the under thread.

-Commencing with the needle at the lowest point of its stroke, the needle starts to raise the needle-thread which, being flexible, bulges out away from the needle to form a loop.

-The loop formed in the needle-thread is then entered by the point of the sewing hook.

-As the needle continues to rise and the hook progresses in its rotation, the needle-thread take-up arm provides sufficient slack thread to be drawn down through the fabric to increase the size of the loop.

-On its first rotation, the sewing hook carries the needle-thread loops around the bobbin case and bobbin, the inside of the loop sliding over the face of the bobbin-case whilst the outside passes around the back, to enclose the bobbin-thread.

-As the needle-thread take-up starts to rise, the loop is drawn up through the “cast-off” opening of the sewing-hook before the revolution is complete.

-During the second revolution of the sewing-hook the thread take-up completes its upward stroke, drawing the slack thread through the material and settling the stitch. Meanwhile, the feed dog has moved forward carrying the material with it and drawing the required length of under-thread from the bobbin.

-The presser-foot guards against the slippage by holding the fabric firmly against the teeth of the feed dog whilst the feed dog is carrying the fabric across the smooth face of the throat plat or needle plate.

Now, that it is clear to us that how a lock stitch is formed, there are many factors that can prevent the correct formation of the stitch. Namely they can be:

(i) Anything which inhibits the formation of the needle-thread loop,

(ii) Anything which prevents a correctly formed loop from being entered by the point of the sewing hook, or

(iii) Anything, which interferes with the free running of either, the needle-thread or the bobbin thread.

Apart from this there are other factors that influence the formation of a satisfactory seam, which are:

(i) The size and type of the needle and sewing thread,

(ii) The relative tensions in the thread lines, and

(iii) The type of fabric and the manner in which it is fed across the throat plate of the machine.

Characteristics of a lockstitch sewing machine:

(i) Uses the least amount of thread

(ii) Produces the flattest stitch

(iii) Gives the best hand

(iv) Allows stitches to blend into the fabric surface

(v) It is reversible and thereby it is used extensively for top stitching

(vi) Tightest and most secure stitch

(vii) Only stitch formation that can be back stitched

(viii) Has the least amount of elongation potential and thereby it is inappropriate to attach elastic or sew knit fabrics or bias seams that are expected to stretch.

THE THREE-THREAD OVERLOCK

This stitch is also known as over-edge, edge-seaming or over-seaming. It is used extensively in the making up of knitted goods and for serging woven fabrics in the tailoring industry.

In its basic form the stitch comprises three threads- a needle thread, and two looper threads. It is the needle thread which actually stitches the plies of fabrics together, whilst the looper-threads interlock with the needle thread above and below the fabric, and with each other on the trimmed edge of the fabric- for which purpose trimming cutters are provided. The interlocking of the looper-threads binds the trimmed edges of the fabric preventing fraying or unraveling.

The stitch has the advantage of very high extensibility. This property makes it eminently suitable for use in readily extensible fabrics, knitwear and the making up of tights