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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Hubert Textiles Pty Ltd
leaner Production - Computerised Ink Paste Mixing

This case study is no longer current with respect to the Company's business activities and operations and was not updated in the review of 2001, but is retained for informational, educational and historical purposes.

Hubert Textiles Pty Ltd operates a textile dyeing and printing business. Significant cost savings and environmental benefits have resulted from the installation of a computerised paste mixing system. A payback of approximately 2.5 years was achieved through reduced raw material and waste costs and efficiency improvements.

Background

Hubert Textiles Pty Ltd (Hubert Textiles), trading as Australian Textile Printing Company, is a medium sized family textile printing and dyeing business. The company commenced operating in 1961 and is located in the Melbourne suburb of Brunswick.

The company prints woven and knitted fabric with multi-colour designs (from one to 12 colours) using flat and rotary screen printing techniques. Additional dye house facilities enable Hubert Textiles to prepare and/or dye the fabric for printing and to finish the fabric after printing.

The printed fabrics are used by a range of customers for the manufacture of bed linen and associated products, clothing and household accessories.

The Process

The screen printing process requires the colour (print paste) to pass through a stencil (the screen) onto the fabric. The print paste used for textile printing is an aqueous suspension of uncoloured stock emulsion, to which colour pigment and other chemicals (auxiliaries) are added (to provide colour fastness and other required end use properties).

The former system involved weighing the chemicals and auxiliaries by hand according to a pre-determined recipe, adding them to the paste and then mixing using a high speed mixer. This coloured paste was then strained through a mesh filter and delivered to the printing machine for use.

At the completion of the print run any left-over paste was either kept for re-use or disposed of to the sewer. The paste containers were also washed with water and the resultant waste water was also discharged to the sewer.

Cleaner Production Initiative

The cleaner production initiative implemented by Hubert Textiles has involved the introduction of a fully automatic, computer controlled paste colour mixing and dispensing system (Stork Brabant's IPS automatic paste dispensing system). The system uses a variable speed gear pump to accurately dispense specified weights of different paste components. After adding all the required recipe components for a particular paste a label is printed and fixed to the paste bucket.

Overview of the new paste mixing system

Overview of the new paste mixing system

The system regularly circulates the various paste components from the storage tanks through the piping system and back to the tanks to prevent settling of solids and to maintain homogenous mixtures.

Advantages of the Process

The benefits from this system have included:

Machinery

The specific benefits from the introduction of the computerised colour dispensing system are discussed in more detail below:

Sampling

Sampling involves printing small pieces of test fabric for colour and design approval by customers. Small quantities of paste are mixed for use in the printing of test pieces. It had always been difficult to weigh out these small quantities of paste. In the past this was overcome by using less concentrated solutions of pigments so that reasonable quantities could be weighed out. The operators used to mix in unit amounts of 1, 2 or 3 kg for example, because this made the recipe calculations easier and a minimum amount of paste was required for a screen even if only a very small amount was actually printed onto the fabric.

The new system has significantly improved the ability to mix small quantities of paste with a very high degree of accuracy. This has enabled smaller quantities to be mixed rather than an amount which is larger than necessary.

Filtering

The new paste dispensing system has completely eliminated the need for additional filtering of the paste. This has eliminated a source of paste loss and eliminated the waste water associated with washing the mesh filters.

Paste Reuse

The new system allows tracking of residual paste left over at the end of a print run. The system is capable of recording and tracking these residual amounts and recalling them next time the same or similar colour is being printed. It is also able to adjust the shade of residual pastes to allow them to be used for different colours. This is an improvement on the previous situation where excess paste was either mixed to produce low grade black pigment or disposed of to sewer.

The system has also reduced the total amount of excess paste by using process parameters to more accurately calculate the paste requirement.

Colour Adjustment

The new system has eliminated many of the inherent inaccuracies in colour matching that arose with manual mixing. There was often a difference between the colour in production compared to that produced during sampling, therefore the recipes were modified slightly using a standard modification factor. In addition each printing machine produced different colour variations. The new colour mixing system has been programmed to take this into account automatically and this has resulted in a much greater degree of colour reproducibility.

In addition some colours were occasionally considered off-shade and had to be adjusted after printing commenced. This required screens and other equipment to be washed while the necessary adjustments were made. Approximately 5 per cent of the 11500 colours mixed every year required adjustment. The wastage of paste and generation of effluent associated with this has been eliminated with the new system. Errors in weighing out pigments in both sampling and production have also been eliminated.

Reclamation of Residual Paste

The increased ability to re-use residual pastes has made it possible to reclaim additional quantities of paste from the screens and associated pipework at the conclusion of a print run. This paste was previously discharged to sewer.

The cost savings associated with the new paste mixing system are summarised in the following table. (Note these cost savings were based on 1995-6 production levels - a general downturn in the Australian textile industry in 1997 will result in a longer payback period being realised).

Production Area Reduction in paste, kg
per annum
Reduction in effluent, KL per annum Cost Saving, per annum
Sampling 2000   $ 2,600
Filtering 4750 170 $ 6,340
Paste Reuse 31700   $ 41,210
Colour Adjustment 4600 288 $ 6,256
Paste Reclaim 34500   $ 44,850
Other savings Reduced labour costs
Improvement in machine efficiencies
Reduction in second grade goods
Reduction in evaporative losses from pigment dispersions
$ 56,440
$ 22,275
 
$ 31,500
 
$ 6,600
Total Annual Savings $ 230,452
Total Project Cost $ 550,000
Payback Period 2.4 years

Cleaner Production Incentive

The main incentive for this cleaner production initiative came from a waste audit that the company conducted in late 1995. The audit identified the amount of wastage associated with various aspects of the company's operations and highlighted the potential savings from using paste more efficiently.

Barriers

No significant barriers to the identification and implementation of this new paste mixing system were encountered by Hubert Textiles.

Date of implementation: 1996
Case Study Prepared: May 1998 by ACCP
The 2001 review found that the company is no longer in business.

ACCP Logo

Hubert Textiles received a no-interest loan under the Cleaner Production Partnership Program for installation of the computerised paste mixing system.