Friday, 2 October 2009

Comparison of Various Printing Techniques



Comparison of Various Printing Techniques


There are various printing techniques available. All have their unique points as well as shortcomings. It would be worthwhile to compare them in order to appreciate and use them for a particular end use.

Handblock Printing: It yields very low production, there is more downtime of ‘machine’. The cost of set up is very less. Very skilled personnel is required to do such printing. The cost of making a design is very less, however durability of design is very low, being defined by durability of block, usually made of wood. The variety of designs is dictated by the skill of the woodworker who carves those designs. The size of design pattern repeat can be larger. There is a limitation of width of the fabric- which is dictated by the width of the table. The printing can be very bold or subdued. In fact, in India there are numerous techniques based on a twin combination of natural dyes and block printing.

Roller Printing: Yields more production , machine downtown is very less, however cost of setup is high- as investment is needed for the maching. The space required is less. Again very skillful operators are required. The cost of making a design is more, as roller has to be carved. The durability of the design is more than a handblock print. Very elaborate and fine designs can be carved on a roller printing. The repeat size is limited to upto 42 cm. Again it has a limitation of fabric width. Very bold and lustrous prints cannot be done on a roller printing.

Flat Bed Screen Printing: Yields more production but less than roller printing as the process is not continuous. There is very less downtime of the machine. The cost of machine and installation is very high. The space requirement is also very high. Very less skilled workers are needed for this printing method. The cost of making a design is less as compared to a roller printing. The durability of the design however is very less, as new screen has to be made after few uses. The quality of designs can be very fine. The repeat of pattern can be very high. Also even a higher width cloth can be printed. The colors can be very bright and bold.

Rotary Printing: It has the maximum production among all printing techniques. The machine downtime is very less. The cost of machine and space requirement is again very high. Less skilled workers can be employed to operate this machine. Cost of making a design is very high. Compared to this the durability of the design is very less. The variety of design it offers and the quality of reproduction is the best among all techniques. Also fabric width can be high for it to be printed. It can yield bright colors.

Transfer Printing: It can do printing only on synthetic fibers such as polyester. One cannot get a ‘tone effect’ in this printing. Even unskilled workers can be used for this technique. However 100% color is not transferred so reproducibility is affected. Paper can’t be used again after one printing therefore its durability is the minimum of all techniques. The cost of making a design is very high. The production is about equal to that of flat bed. There is very less downtime of the machine. Space requirement is very less, infact, less than any other printing technique.

Now that you've finished reading this post, what are you going do? You should go join the Forum.

Tuesday, 29 September 2009

Major Warping Defects- On Sectional warping



Snarlings and Overlappings

These are caused by irregular yarn tension. The broken end is not tied-up by the operative with the yarn end on the drum.

Different lenghts of sections, High Wastage Rate

This is caused by over-or-under warping of sections, untimely laying of lease cords due to faulty operation of the counter and the carelessness of operative.

Overlapping/Excessive Distance

The sections overlap each other or there is an excessive distance between them. This is caused by support improperly set and the careless of warper operative.

Stripiness in the Warp

This is caused  by improper mixing of raw material

Irregular Winding

Irregular winding on the warper's beam which is displaced towards one end. This is due to improper position of the weaver's beam in warp beaming.

Different lenghts of Ends

It also includes irregular distribution of the section in the weaver's beam width. This is caused by improper fixing of section ends to the weaver's beam.

Excessive or insufficient number of yarn ends in the warp

This is caused by improper calculation at gaiting.

Warp Beaming on a defective weaver's beam

This is caused by carelessness of the assistant foreman and the warper operative.

Incorrect Laying of lease cords, or their absence in some sections

Again this is caused by carelessness of the warper operative.      

Now that you've finished reading this post, what are you going do? You should go join the Forum.

Monday, 28 September 2009

Suitability of a fiber for a blend



Fibers in a blend are chosen keeping in mind various properties of the constituent fibers. Thus a blend is chosen which gives the best of properties of the different constituents of the blend. The properties that are considered can be strength, absorbency,crease resistance, resistance to abrasion, resistance to heat, bulkiness,resistance to pilling and Dimensional stability.All the fibers do not have all the properties that are desired. This is the very reason why blend is chosen.

Cotton has moderate strength and dimensional stability. However, it is excellent in absorbency, resistance to heat and pilling. It has an average resistance to abrasion and poor bulkiness properties and crease retention.Thus it is added in the blend to have excellent absorbency properties.

Viscose Rayon has excellent absorbency, resistance to heat and pilling. Thus it is similar to cotton in these properties.It has however, poor resistance to abrasion, bulkiness, crease retention and stability. It has an average strength. It has absorbency properties similar to cotton. It is also cheaper than cotton.

Acetate Rayon has excellent resistance to pilling and stability. It has moderate resistance to heat and average absorbency, crease retention and stability. However its resistance to abrasion is very poor.

Wool has excellent absorbency, bulk and wrinkle resistance. However, it has poor stability. It has moderate abrasion and heat resistance. Its crease retention, resistance to pilling and strength can only be considered as average.

Nylon has excellent strength, stability and abrasion resistance. However, It has poor absorbency and bulk. It has moderate crease retention and average resistance to heat and pilling.

Polyester has excellent strength, stability, crease retention and abrasion resistance. However it has poor absorbency, bulkiness properties and resistance to pilling. Its resistance to heat is average.

Acrylic has excellent bulk and stability. It has moderate resistance to heat and average crease retention and strength. Its resistance to abrasion and pilling and absorbency are very poor.It is similar to wool in most of the properties. It is also cheaper than wool.

Modacrylic has excellent stability and bulk properties. However its absorbency, resistance to heat and pilling is very poor. It has average strength, resistance to abrasion and crease retention.

Polypropylene and Polyethylene have excellent stability and strength. They have poor absorbency, bulk and heat resistance. The have average crease resistance and resistance to pilling.

Now that you've finished reading this post, what are you going do? You should go join the Forum.

Tuesday, 1 September 2009

Seam Strength Vs. Seam Slippage



Difference Between Seam Strength and Seam Slippage

Both the parameters measure the performance of seam. Seam strength referes to the strength when seam finally ruptures or when the fabric breaks.

However before rupturing there is an unacceptable opening in the seam which makes the seam 'failed' commercially even when there is no visible rupture. Seam slippage measures that.

Seam strength depends upon stitch type, thread strength, stitches per inch, thread tension, seam type and seam efficiency of the material.

Seam slippage depends upon the stitch rate, the weave structure of the fabric and the width of the seam allowance.  

There is another term called 'yarn slippage' which measures the shifting of warp yarn over weft yarn to render the garment unusuable. 

Yarn slippage depends upon a low number of warp or filling yarn, two shallow seam allowance, too tight a fit and improper seam construction.  

Find Pictures of Seam Quality Defects here.

Total Pageviews