SMC technology aids automation at Denby

Citation

(1998), "SMC technology aids automation at Denby", Assembly Automation, Vol. 18 No. 2. https://doi.org/10.1108/aa.1998.03318baf.002

SMC technology aids automation at Denby

SMC technology aids automation at Denby

Keywords Automation, Denby Pottery, Pottery, SMC

Pneumatics technology from SMC is playing a vital role in the automation of a previously manual production process at the Denby Pottery in Derbyshire, UK (Plate 2). The pottery, one of the world's most successful producers of quality oven and tableware, has invested more than three quarters of a million pounds in an automated production system for its large cookware products.

The new system, which is one of the first to make use of innovative microwave drying technology, was commissioned in April last year and, in the first six months of production, has enabled Denby to more than double throughput, while reducing labour costs and improving product quality, claims SMC.

In essence, the automated system combines two manufacturing lines in a single production cell; one line manufacturing the base pot, the other manufacturing the lids. Both lines can operate simultaneously or individually, depending on the product type and stock requirements and are designed to produce clayware to the first kiln stage.

Similar processes are used on both lines in the system, which is CNC controlled from a central point.

Using the base manufacturing line to illustrate the procedure, clay billets are manually loaded into a pug mill, which processes the clay and extrudes it, in a precisely measured quantity, directly into one of a series of plaster moulds, which then indexes to an initial forming station.

Plate 2 SMC Technology aids automation at Denby

At this station an internal roller is lowered into the moulds, which rotates at an extremely high RPM, to form the basic shape of the pot. A trimming device is brought simultaneously against the top edge of the mould, to remove any excess clay, which is suctioned directly away.

From the forming station, the moulds are indexed to a first stage drying process, which is where the microwave technology is employed. In its original state, the clay used by Denby contains 19 per cent moisture; at the first drying stage this is reduced to 15 per cent. Using conventional drying techniques, this process takes hours, however, using the microwave drying system, which is capable of drying up to 78 pots at a time, the process takes just 12 minutes.

The drying process causes the clay to shrink slightly from the edges of the mould, enabling each pot to be removed quickly and effectively as it exits the drying system, using a pneumatically controlled pick and place system.

Vacuum technology is used throughout in the handling of the pots, to avoid witness marks being left in the clay. The pots are removed from the moulds using a vacuum system comprising four large diameter suction pads, with the pots being picked internally and placed on a covered conveyor for transfer to a second stage drying process.

SMC Series ZM two stage vacuum ejectors are employed throughout the system, in conjunction with vacuum filters, to ensure high quality vacuum generation across all pick and place functions, with the filters providing a safeguard against the ingress of clay dust into the system.

The conveyor stops at an off load point for the secondary dryer; a warm air system, where the moisture content is reduced still further to 11 per cent. At this point, an SMC CDG clean line cylinder is used to actuate a handling device, which centralises the pots on the conveyor in the correct position for pick and place to the dryer.

Up to 200 pots at a time are loaded into the dryer, where they remain for approximately 45 minutes.

On exiting the dryer, a vacuum pick and place unit, which operates on a horizontal carriage and uses an SMC MY1B rodless cylinder in the X traverse, places the pot on the first of three spindles, in a fully automatic multi-station turning system.

At the first station, a shaping tool is applied to produce an initial profile, at the second station final shaping is performed and, at the third station finishing operations such as smoothing are carried out.

The pots are transferred from station to station using a second horizontal carriage type pick and place system, which then removes the finished pot and places it on a conveyor where it exits to a manual station and the handles are applied. The pots are then stacked for transfer to the kilns for firing.

Typical throughput rates are 2.2 pots per minute, with the line running a shift which produces 800 pots per day.

Because of the dusty environment in which the system operates, coupled with the extensive use of vacuum, high quality air preparation is essential to the successful operation of the line.

To this end, the latest modular air preparation equipment, from the recently extended SMC range, is used throughout. For example, Series AF filters are used extensively for the removal of contaminants from the air flow. The filters feature a unique 5µm poly-element, which offers high flow rates comparable with a 40/µm filter.

In addition, Series AS 3000 flow speed controllers are installed in line, enabling constant speeds to be set quickly and easily, with accurate control of flow speeds provided, even at low velocity.

At the multi-station turning system the SMC Series IR precision regulators, are used to precisely control the contact pressure of the turning and trimming tools against the clay, which are guided by small bore precision cylinders. Extreme accuracy is essential in this area of the process, as any fluctuations in the pressure of the cutting knives or trimming tools, will potentially damage the pot.

The pneumatic content of the entire automated system is vast. The machine was manufactured in Japan, by a leading supplier of equipment to the ceramics industry and uses SMC almost exclusively throughout.

SMC Series CQ2 compact cylinders, Series CDG clean line cylinders and a comprehensive selection of one touch fittings and tubing, including Series KX rotary fittings on the vacuum heads, all contribute to the successful operation of the line, enabling Denby to continue to meet production targets, which are increasing almost daily in line with consumer demand.

Mark Thomas, production director at Denby, explains that, "Our international competitors are increasing in their awareness of the trends in consumer demand towards products that are compatible with a casual lifestyle, and consequently competitive pressures are increasing in all markets, particularly in the UK. In response, Denby has accelerated the introduction of innovative new products; increasing production throughput and improving quality, while at the same time, reducing manufacturing costs, through the introduction of automated manufacturing processes, such as the cookware line.

"The management focus is very much centred on brand development and manufacturing efficiency, the latter being continually developed through our relationships with suppliers of high technology automation products, such as SMC."

Contact Jackie West, SMC Pneumatics (UK) Limited, Vincent Avenue, Crownhill, Milton Keynes MK8 0AN. Tel: +44 (0) 1908 563888. Fax: +44 (0) 1908 561185.