Case Study : Don & Low Case Study
Many of Don & Low's systems were not Millennium compliant and Don & Low decided to replace all of their business systems. S-Plan had been identified as the best fitting scheduling package prior to the millennium project and the fact that they were strategic partners with the selected ERP supplier reinforced the earlier decision.
Don & Low are manufacturers of industrial textiles. They have two divisions: Wovens and Nonwovens. The main woven markets are floor coverings, furnishing fabrics, groundcover and geotextiles. The main nonwoven markets are construction, agritextile, airline and filtration.
Wovens The manufacture of woven cloth follows the stages described below:
- Extrusion: the creation of the tapes which are to be woven together
- Beaming: the assembly of warp tapes on to beams for insertion into the loom.
- Weaving: the creation of the cloth from the tapes.
A roll of cloth is typically around 1000 linear metres long and the width is from 3 to 5 linear metres. The tapes which run the length of the cloth are called warp tapes and are assembled on a beam (a large spindle which is the width of the loom). The tapes placed on the beam will be 20,000 m long and can therefore produce 20 individual rolls of cloth. The beam is attached to the loom ready to start weaving. The tape which is passed across the width of the cloth using a shuttle type arrangement is called the weft tape. The frequency of tape insertions typically ranges between 26 and 90 times every 10 cm of cloth. A different type of cloth can be produced by changing the type of weft tape or the number of weft tapes per 10 cm length ( the construction of the cloth).
The Nonwovens process is thought of as a two-stage process but the model in S-Plan can lead to a four-to-five stage process. Nonwovens has three primary lines which produce cloth to a fixed width. Two of the machines are 3.2 m wide and one is 2.4 m wide. The molten polymer is extruded through a die and falls randomly on to a belt. The cloth however can be cut on line using up to 6 blades per metre width of the line. This introduces the opportunity for Greycon's X-Trim, trim optimisation product. Often the cloth will have to go to a finishing process to be trimmed further, as some end uses require widths as small as 2 cm.
Scheduling with S-Plan: Wovens, Making to Forecast
Although it is the third stage of production, weaving is the crucial process to schedule (sequencing on extrusion and beaming are defined thereafter).
Performance & Flexibility
There are 244 looms at Don&Low Wovens which required S-Plan to be extended to cope with such a large number of workcentres. The sheer quantity of looms alone necessitated a scheduling tool! The processing rate of a machine may depend on some of the order criteria (e.g. number of weft tapes on a cloth). Adjust Rates were used to model this situation elegantly.
In the Wovens business, 50 % of orders/call-offs are placed the same week as delivery is expected despite lead times of 5 to 6 weeks. Accurate forecasts are therefore paramount! Weekly planning meetings between the sales and production departments are held to maintain the rolling 13-week forecast as accurately as possible. The forecast is entered into a fixed format Excel spreadsheet which is then automatically loaded into the ERP system. Any changes in the demand for cloth identified at the meeting are entered by the planner in the ERP system and this is then transferred automatically to S-Plan via Integration Manager. The order enters S-Plan and when first scheduled resides on a workcentre known as the Order Pool. The ERP system requires two main pieces of information to be passed back from S-Plan: the tasks start and finish dates/times and the beam numbers to which the production orders will belong.
An updated loom plan report is then produced to reflect the new orders, beams and updated dates/times and will be discussed at the next Planning meeting. The cycle is complete!
Built to fit Don&Low requirements
Greycon designed a new S-Plan extension, DBO (The Dynamic Beam Optimizer), to allow the planner to place production orders onto a beam through a user-friendly graphical interface. The planner creates the beam in S-Plan, defines its specifications (properties of the cloth) and places production orders on it. The beam is then represented on the Gantt Chart as a group of orders. Within DBO production orders can be moved to other beams and even split or merged. There is full validation and DBO will warn when a production order for cloth is placed on a beam with a different specification. Progress on the beam is displayed in DBO and the range of permissible actions constrained appropriately. The manufacture of cloth has many idiosyncrasies which are difficult to model in S-Plan. Greycon has therefore developed DBO in a very flexible way to cater for these special cases.
Weaving is currently the only stage (for Wovens) fully implemented in S-Plan: the 32 extrusion lines and 3 beaming machines will be included to S-Plan in the future.
Scheduling with S-Plan & X-Trim: Nonwovens, Making to Order
Unlike Wovens, all the stages at Nonwovens are linked in S-Plan so if there is a bottleneck at finishing then the upstream processes will be scheduled appropriately.
Nonwoven's business is 99% make to order and the lines are planned one month in advance. When an enquiry is received from a customer, it is entered into the ERP system and is then automatically transferred to S-Plan via Integration Manager. The enquiry is scheduled in S-Plan as a reservation. A date is returned to the ERP system which can then be viewed by the Sales administrator. If the date varies significantly from the customer required date, the Sales administrator will contact the customer, otherwise an order is placed on the ERP system and the enquiry in S-Plan is replaced by the firm order.
Where there is a need, the planner will select the production orders to be deckled using X-Trim and the resulting pattern will have a decklesheet reference. The production order and deckle information is passed back to the ERP system. The ERP system has been modified so that, on entry of the deckle reference, all production order data is available and appropriate bar-coded tickets are generated when product is taken off.
The real benefit which has been experienced at Nonwovens is in the use X-Trim. The amount of waste that has been saved through the use of X-Trim has yet to be established but X-Trim has halved the amount of time spent seeking optimum deckling.
The learning curve has been very steep and the application of S-Plan along with its integration with the ERP package has provided many challenges. At the time of writing, a spreadsheet system is still being run in parallel with the S-Plan system. A new modification to the ERP system will soon remove the need for this parallel system.
At Wovens, the Greycon solution was arrived at after an intense period of specification and development. At Nonwovens, the solution is even more complex and has evolved in parallel with the existing manual system. Greycon staff have played a leading role in the implementation of their products to new and unfamiliar challenges. There are plans to introduce S-Plan into extrusion and beaming, ultimately leading to a planning chain covering all processes.