Friday, September 7, 2012

Sewing machine; Comparison between Pegasus sewing machine and Yamato sewing machine.

Pegasus and Yamato are the world class brand, both company are produce world class sewing machine. Both company have Single needle lockstitch sewing machine, 2 needle lockstitch sewing machine, Overlock sewing machine, Flatlock sewing machine, Feed of the arm sewing machine,Button hole and button attach sewing machine and many more. I am going to compare between Pegasus sewing machine and Yamato garments sewing machine. 

Sewing Machine type
Pegasus  Sewing Machine
Yamato   Sewing Machine
Over lock/ neck join Sewing Machine
Normal neck join sewing machine of Pegasus is easy to operate and handle. It is easy to learn for an operate. Production rate high.
To install neck sewing machine joint three persons (technical manager, sr. service engineer, service engineer) take three days. From this point of I think that mechanical function of m/c this difficult and which may take long time to repair (if necessary) for a mechanics. Beside this it difficult to an operator to operate and production rate is lower than others.


Over lock m/c
Normal over lock of Pegasus is easy to operate. Its motor speed is high & production rate is also high. Over lock width can be increase at maximum label. It can fulfill every buyer requirement.
This  sewing machine is good. It can be easily operate and user friendly. Its production rate is less than others but its production quality is good. If it is in operation, alter quantity will be reduced.

Flat lock m/c or bottom hem m/c
Motor speed is high. Easy to operate. Production rate is also high (230-260 pcs)/hr.
For bottom hem operation always needs to keep hand above the m/c bed which makes an operator uncomfortable. If operator keeps hand below then body hem cut, hem makes with raw-edge & sometimes occurs puckering. And its production rate is less then others (170-200 pcs)/hr.
Back tape m/c
Pegasus has no back tape sewing machine.
This  sewing machine is good enough for back tape attach than others. But technical manager told that this m/c can not be idle i.e. by adding extra parts or accessories it can be used for body hem, neck t/s, arm hole t/s etc. But they did not show it.


If thread cut in Yamato sewing machine it requires spanner to wear thread and time consuming but in others m/c no spanner to wear thread, which save time. Personally I have talked to maintenance manager of Inter Stop and Dulal Brothers about Yamato sewing machine. They told me that Pegasus sewing machine is better than Yamato sewing machine because parts of this machine are not available, costly and can be purchased from their agent.
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Work measurement; A systematic way of work study



work measurement:
Work study is scientific method which ensure measurement of work content of a job and takes recourse to better method of doing it and thus realizes the best utilization of human machinery and other resource of an organization. Work measurement is very important part of work study and productivity improvemant.
Work measurement used to determine:
- Time required to complete one element of operation or
-Amount of work that can be performed by one operator in a specific segment of Time

Work Measurement Techniques are:
1.) Time Study
2.) Judgment or past experience of the engineer / production manager
3.) Predetermined Time systems
4.) Standard Data
5.) Operator Reporting
6.) Work Sampling

1.) Time Study
Time study is a systematic technique for determining the amount of time required for a qualified, well trained person, working at a normal pace to perform a specific operation. The person conducting the study is a Time Study Analyst But one thing needs to be remembered, and that is that in any situation that requires one person to determine how much work is fair to expect from another person, hard feelings may result. Hence a Time Study Analyst has a task of great responsibility.

2.) Pre-determined Motion Time Systems (PMTS)
Production Standards are established for new styles before the style goes into production The basis is historical data for hundreds of replications of basic motions and elemental times that have been averaged and converted to standard times for a specific motion. The rates are based on the time taken to execute a method. The method of motion sequence is established first, and the time value or rate is identified for the motion specified. Operation specifications identify the specific method that an operator is expected to follow.
GSD, Mod Sew are example of PMTS they identify times values for specific motions required in garment production and are available as computer software that garment manufacturers can purchase.

3.) Judgment
• Time Study may be, time consuming and costly
• For small orders a style may not be in production long enough for Time Study
• This can provide only approximate values

4.) Standard Data (Garment Synthetics)
Firms may also collect their own data for repetitive operations with similar characteristics and develop their own standard data sets for specific operations used in the same way as predetermined motion-time data except that the data sets are specific to the firms quality standards, equipments and procedures.
Standard data may be developed for:
• Operations,
• Components,
• Styles, and
• Used for preliminary costing and design decisions as well as cost estimating.

5.) Operator Reporting
Relates to the volume completed during the time spent. There are no specified methods or output expectation. The amount of work completed in a specific time frame is often inconsistent and may be unreliable. This type of work measurement provides very little information and little incentive for increasing work efficiency.

6.) Work Sampling
It is a work measurement method that is not concerned with how fast a unit is completed but rather which machines are used and activities pursued the job over an established period of time. When production standards are needed for operations that are not highly repetitive, work sampling is a good choice.

 -Determines the activities involved
 -Amount of time spent on the various activities
 -Equipments used.
Thus the managers can estimate the production of time a worker is engaged in work activity. The proportion can then be used as a performance standard.

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Monday, September 3, 2012

Modular Garments Production System

Modular Garments Production System 
There are so many popular apparel garments production systems, such as


-Progressive bundle system
-Unit Production System
-Modular Garments Production System
-Combined 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 minifactories 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. This 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

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Progressive Bundle System of Apparel garments production

 of apparel garments manufacturing could be summarized :
There are so many popular apparel garments production systems, such as


-Progressive bundle system
-Unit Production System
-Modular Garments Production System
-Combined garments Production System

The progressive bundle system (PBS) of apparel garments production gets its name from the bundles of garment parts that are moved sequentially from operation to operation. This bundle 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 apparel 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.
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Unit Production System of garments manufacturing

Unit Production System of garments manufacturing:
There are so many popular apparel garments production systems, such as


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.
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Reasons for Studying Textiles:



A study of textile engineering will show, for example, why certain textile fabrics are more physically durable and therefore more serviceable for specific purposes. It will explain why certain textile fabrics make cool wearing apparel as well as give an impression of coolness when used as decoration. The matter of cleanliness and maintenance must also be estimated before purchasing when that is an important factor.

Complete knowledge of textile engineering will facilitate an intelligent appraisal of standards and brand of apparel garments merchandise and will develop the better ability to distinguish quality in textile fabrics and, in turn, to appreciate the proper uses for the different qualities. A result, both the garments consumer merchant and consumer customer will know how to buy and what to buy, and salespeople will know how to render good service to those consumers who have not had the advantage of a formal course in textile engineering.

Great strides have been made in the textile, garment industry, and have markedly influenced our general economic growth. The prosperity and growth of related industries, such as retail apparel stores, have produced broader employment opportunities. Competition for the textile consumer’s dollar has fostered the creation of new textile fibres with specific qualities to compete with well-established textile fibers. New fiber blends have been created to combine many of these qualities into new types of yarns with new trademarks. There are also new names for textile fabrics made of these new textile fibers and yarns. New finishes have been developed to add new and interesting characteristics to textile fibers, yarn and fabrics.

This welter of creativity and the myriad of trademarks present a challenge to the textile consumer, who is sometimes knowledgeable but frequently confused. Yet one need not be. Without being overly technical, this information can be easily understood and consequently very useful to the textile consumer in business and personal to the textile consumer in business and personal life. All of this information can be adopted for such utilitarian benefits as economy, durability, serviceability and comfort, as well as for such aesthetic values as hand (or feel), texture, design and color of textile and apparel garments products.

In the study of textile engineering, the student’s initial interest will become an absorbing interest when they discover the natural fascinating of textile fabrics and their cultural associations, particularly when factual study is supplemented by actual handling of the textile and apparel materials. The subject will seem worthwhile as they become familiar with illustrative specimens and fabrics and being to handle and earn to compare the raw materials of which fabrics are made as well as the finished consumers goods.

USEFUL PURPOSES OF STUDYING TEXTILE PHYSICS:-
The useful purpose of studying textile physics are:-
1. To understand the detailed structure of fiber, yarn and fabrics
2. To understand the properties of fiber, yarn and fabrics.
3. To understand the behavior of fiber, yarn and fabrics in end condition.
4. To become able to design fiber, yarn and fabric having the required properties to meet the end-use requirements.
5. To identify faults & their causes & nature in fiber, yarn and fabrics.
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Sunday, September 2, 2012

Textile physics; Introduction to textile physics

Textile physics is very important subject for textile engineers or textile related students. I want to share my experience in this site. I am going to discuss about bellow topics. So be with me for more update.

Why study or learn                                                                                                    
Why study textiles                                                                                                     
Why study textile physics                                                                                          
Textile raw materials                                                                                                  
Classification of fibers                                                                                                                                    
Engineering approach to fibers, yarns and fabrics                                                     
Importance of textile structures for Engineers                                                                      
Physical and Mechanical properties of various fibers                                    
Textile properties developed by drawing                                                                  
Design and other fiber attributes                                                                               
Essential and desirable properties of textile fibers                                                    
Influence of fiber fineness                                                                                         
Miscellaneous properties of fibers                                                                             
Flexural rigidity of textile fibers                                                                                
Fiber migration                                                                                                           
Measurement of fiber migration                                                                                

PHYSICS FOR TEXTILE FIBRE, YARN AND FABRIC
Definition of yarn                                                                                                      
Factors affecting yarn strength                                                                                  
Parameters affecting physical properties of yarn                                                       
Classification of yarn                                                                                                 
Classification of yarn based on physical and performance characteristics                
Description of yarn                                                                                                    
Idealizes structural diagram of some yarns                                                                
Continuous filament and staple yarn structure                                                          
Fundamental structural features of yarn                                                                    
Yarn designation                                                                                                        
Relative consumption of yarn                                                                                    
Sewing thread                                                                                                            
Thread sizes                                                                                                               
Thread selection                                                                                                         

Importance of twist                                                                                                   
Types and direction of twist                                                                                      
Bedding or nesting                                                                                        
Determination of twist                                                                                               
Twist effects                                                                                                              
Angle of twist and twist factor                                                                                 
Effects of twist on yarn strength, extensibility and luster                                                
Geometry of twisted yarn                                                                                          
Idealized twisted yarn geometry                                                                               
Various comments on idealize yarn geometry                                                           
Yarn size and twist multiplier                                                                                    
Optimum twist factor                                                                                                            
Fiber packing in yarn                                                                                                 
Open packing of yarn                                                                                                
Hexagonal close packing of yarn                                                                               
Real yarn packing                                                                                                      
Concentrating and disturbing factors                                                                                    
Observed packing of fibers in real yarn                                                                     
Twist in relation to yarn bending                                                                               
Relation among twist angle, twist factor and yarn count                                          
Equation for yarn diameter                                                                                        
Equation for specific volume of yarn                                                                        
Show that d=4.44 x 10-6ÖTex / Density                                                                    
Relation among twist, diameter and twist angle                                                       
Estimation of Schwarz’s constant                                                                             
Yarn luster                                                                                                                 
Twist contraction and twist retraction                                                                                   
Limit of twist                                                                                                             
Contraction factor and retraction factor                                                                    
Derivation of expression for prediction of filament strain                                        
Limitations of Platt’s low strain equation                                                                  
                                                    

Geometry                                                                                                                   
Cloth geometry                                                                                                          
Reasons for studying cloth geometry                                                                                    
Weave and weave notation                                                                                        
Crimp                                                                                                                         
Warp crimp and weft crimp calculation                                                                     
Crimp percentage and take up percentage                                                                             
Distinction between crimp % (C) and take-up %(T)                                                 
Relationship between crimp (%) and take-up (%)                                                     
Pierce’s Flexible thread model                                                                                   
Importance of crimp on fabric properties                                                                  
Fabric behavior during tensile testing                                                                        
Measurement of crimp                                                                                               
Principles of edged crimped yarn                                                                              
Crimp measuring instrument                                                                                      
Pierce’s  model for plain weave                                                                                 
Equation for pick spacing (P2) and end spacing (P1)                                                
Equation for maximum warp yarn displacement (h1) and weft yarn displacement (h2)         
Dependence of crimp percentage                                                                              
Crimp interchange                                                                                                      
Equation for crimp  interchange                                                                                
Warp and weft yarn jamming                                                                                    
Equation for warp and weft yarn jamming                                                                
Biaxial, tri-axial and balanced structure                                                                    
Equation for rigid thread model                                                                                
Why rigid tread model was introduced                                                                     
Effect of yarn crimp on fabric properties                                                                  
Concept of similar cloth                                                                                             
Cover factor                                                                                                               
Yarn and fabric strength relationship                                                                                    
Handle, drape and shear                                                                                            
Measurement of drape ability                                                                                    
Some tensile properties of fabric                                                                                                                   

Electrical properties of textiles                                                                                  
Dielectric properties of textiles                                                                                  
Polarization and related effects                                                                                 
Power factor and dissipation factor                                                                           
Measurement of dielectric properties                                                                                                                                                                                 
Preparation of a test condenser                                                                                  
Measurement of impedance by Scherring’s bridge and resonance method               
Factors influencing dielectric properties of textiles                                                   
Electrical resistance of textiles                                                                                   
Conductors, semiconductors and insulators                                                              
Conduction of electricity in textiles                                                                          
Influence of dielectric constant on ions                                                                     
Normal, excited and ionized atom                                                                             
Electrical resistance of textiles                                                                                   
Measurement of resistances of textiles                                                                      
Specimen preparation for measuring resistances of textiles                                       
Influence of various factors on resistance of textiles                                                
Static charge                                                                                                              
Explanation of static phenomenon                                                                            
Theories of static charge                                                                                            
Measurement of charge in slivers by Faraday’s cylinder and Medley’s method                     
Generation of static charge in polymers                                                                    
Amphoteric behavior of keratin                                                                                 
Piezo and pyro electric charges                                                                                                                                                       
Leakage of static charges in air                                                                                  
Leakage of static charges in perfect insulators, moderate insulators, & conductors                              
Problems of static charges in textile mills                                                                  
Minimization of static charges in textile mills                                                           
The present view about static charges in textiles      

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