Reply To: Star Paper Mill (Feniscowles)

Star Paper Mill (SPM), Feniscowles. Production processes 1961-1970

In 1961 the SPM was owned by Kymmene Aktiebolag of Finland having been bought in 1930 and later had bought a second paper mill in Barnsley.

The following descriptions are based on the contents of a ‘work diary’ written as an engineering student apprentice at SPM 1963-1967. A few recollections from memory have also been added.

The Mill’s manufacturing activities could be split into four groups, stock preparation, coating preparation, paper production and paper finishing.

1) STOCK PREPARATION

Stock preparation started with the raw materials, softwood pulp and hardwood pulp (imported from Finland), arriving at the mill by road transport in the form of wood-pulp sheets that had been packed as rectangular shaped 3cwt. (three hundred weight) bales.

The first task in stock preparation was to transport the bales of pulp from the outdoor storage stack using an overhead crane and fork-lift truck to the metal-slat conveyor situated on the first floor level leading to the top of an hydrapulper. Water was added to the hydrapulper first and then the pulp bales added by means of the conveyor. The vertical rotor of the hydrapulper would then stir the mix and break-up the bales to form a coarse pulp. The hardwood and softwood material were pulped separately and each batch was pumped into hardwood and softwood dump chests ready for the refining stage. The softwood was passed through a series of Morden Refiners and the hardwood was passed through a Claflin Refiner. (Note: I seem to recall that the Claflin Refiner was a powerful machine, the motor requiring a 33,000 volt electricity supply direct from the National Grid).

Refiners consist basically of a barred conical plug rotating inside a stationary barred matching conical shell. The relative position of the plug can be adjusted such that the amount of work done on the stock can be controlled. The many variables in the construction of a stock refiner include, the bar material, the thickness of bars, the shape of the bar edges, the applied pressure between the rotating and stationary bars, the size and distribution of the rubbing surfaces, the relative speed of the rubbing surfaces and the physical size of the equipment. The process of stock refining results in the shortening of the pulp fibres and increased fibrillation, i.e. shredding the ends and outer wall of the fibre thus swelling the fibre material. For swelling to occur it is necessary for the outer walls to be ruptured. The immediate control of this refining process was achieved by measuring the temperature difference between the refiner stock inlet and outlet which was considered to be proportional to the work done on the stock. By keeping the temperature different constant refined stock with very similar characteristics could be produced continuously. Periodic liquid quality control samples would be taken for laboratory analysis.

The refined stock was stored in the Refined Chests, the hardwood and softwood stock still held separately at this stage, and each Chest was fitted with a pressure and consistency (ratio of fibre to water) controlled ring-main system from which stock could be drawn into the Blend Chest. Such controls enabled any type of machine furnish to be produced with consistent characteristics.

In addition to the hardwood and softwood feeds a third supply consisting of ‘coated broke’ was fed into the Blend Chest, also under consistency control. Coated broke was paper made previously but had not met the required quality standard or was clean waste from the various finishing processes that had been re-pulped. Colouring dyes are also added in the Blend Chest under flow control by magnetic flowmeters.

From the Blend Chest the stock was fed through a Jordan refiner for final beating. The stock was consistency regulated and then stored in the Fine Chest. From there it was fed into the ‘Stuff Pot’ (a simple overflow weir) from which the flow was controlled in order to get the correct even sheet substance on the wire Next, the stock was diluted with recycled white-water and china clay was added (loading the paper) as a means of improving the surface finish of the final sheet as well as increasing its opacity and improving printability. The diluted stock was then pumped at pressure to the Bauer cleaners, which were a bank of small diameter tubes using centrifugal force to remove any solids heavier than the stock, these solids being drawn-off from the central region while the lighter stock was flung to the outer region of the tube and fed continuously through a Centri-Screen in order to reject any remaining knots and lumps from the stock before being fed directly to the papermaking machine headbox to begin the sheet forming process (see 3 below).

2) COATING PREPARATION

The two principle substances used in the coating mix were china clay and starch. Both of these ingredients arrived at the Mill in fine-powder form packed in 1 cwt. paper bags. The coating was produced in batches with the clay, starch and small quantities of whitener and dyes added to water contained in a tank fitted with a stirring mechanism. The resulting solution was known as Premix and was composed of about 60% solids. The Premix had to be cooked before being used on the papermaking machine but once cooked it could not be stored, hence, batches of premix were drawn off and cooked in amounts demanded by the papermaking machines. The cooking of the Premix was achieved by steam injection at a minimum temperature of 195 deg F. After cooking the mix was cooled using tubes through which cold water was circulated. Small quantities of additives, e.g. aquapel, stearate and latex were added, dependent on the type of paper being produced. The coating mix was then pumped directly to the coating reservoirs formed by the transfer rolls of the coating section of the paper machine (see below and the M/c layout in the previous submission) using Mono pumps which were designed to cope with high solid content fluids.

3 PAPER PRODUCTION.

The stock, having arrived at the Papermaking Machine (Pm. M/c) from the Centri-Screen, (see 1 above) was fed into the Headbox which acts as a reservoir for the stock. The Headbox also plays an important part in keeping the stock’s fibre in suspension so that stock of a uniform consistency would be fed onto the wire section of the Pm. M/c. The headbox had a narrow slit, the slice, the full width of the Pm. M/c though which the stock flowed by gravity onto a continuously moving wire mesh. The consistency of the stock leaving the Headbox would have been between 99.5 and 99.9% water by weight.

SPM had a comprehensive Quality Control Laboratory and implemented many continual checks on the production preparation processes and the products in an attempt to ensure that the results of all the production operations conformed to the desired specifications.

SPM had two papermaking machines, both Fourdrinier type machines, No1 M/c producing a paper-width of 120 inch and No2 M/c a paper-width of 180 inch. Both machines had on-machine coating capabilities. This type of paper-making process and its operation is well documented elsewhere so no further description is given here but the type of mechanical drive for each of these machines may be of some interest.

No1 M/c was directly mechanically driven by a vertical cylinder steam engine fitted with a V-belt drive to a line-shaft running parallel to and the full length of the papermaking machine with flat-belt and cone pulley take-off drives to the various sections of the machine. The use of cone pulleys provided the relative speed adjustments needed for each of No1M/c’s sections, the position of the belt on the cone determining the speed setting. In 1970 the intention was to replace the steam engine with an Allen steam turbine but I cannot confirm that this was carried out.

No2 M/c was driven by sectional DC motors electrically synchronised and powered from a 500kW generator driven by a vertical cylinder Browett & Lindley steam engine which also drove an exciter situated remotely from the motor drives. The exciter fed No2M/c drive motor field coils and also the control circuits of No2 M/c’s drive system. The motor armatures were fed by the generator. The speed of the No2 M/c was controlled by the two DC motors driving the main drying section. A layshaft from this section ran the full length of the M/c and controlled the speed of the other sections by the use of an electro-mechanical differential regulation system. Control of the whole paper-machine speed was achieved by increasing or decreasing the voltage supplied to the armatures of the motors. The fine adjustment to the relative speeds of the M/c Sections, which is necessary to keep the paper sheet in tension, was achieved via a cone pulley and belt system attached to each section motor shafts, similar in principle to the purely mechanic drive of No1. M/c.

Both M/cs were operated continuously from 6am Monday to 12noon Saturday. Saturday afternoon was M/c cleaning time and Sunday was the main engineering maintenance period. There was a two-week annual shutdown in which major engineering projects on the M/cs were carried out.

One recollection is that after unusually heavy rainfall parts of the Mill were susceptible to flooding which could prevent No2 M/c from operating. SPM was situated in a valley with the River Roddlesworth running in a large tunnel-like culvert with the Mill built over it. Normally the river was of small volume and occupied only a small portion of the culvert floor but after very heavy rain, the volume and flow rate would increase dramatically until the water level was at the culvert roof level. Under this extreme condition a few parts of the mill were likely to flood. The most likely area was the basement of number No2 M/c. As the water level rose the first casualty was the sump area which normally drained into a channel running at the side of the culvert but under flood conditions this sump would be filled directly by the river water. Although addition flood barriers had been built across the basement passsageway in order to contain the flood to the sump area, the limit of tolerance of the flood level was the lowest felt run of the drying section and if the flood level reached the height of this felt then. irrespective of the flood barriers, the machine had to be stopped.

Both No1 & No2 M/c were fitted with paper coating sections as an add-on processes to the paper production. This section used a series of rubber covered rolls to apply the coating to the surface of the paper sheet. In total there were 9 transfer rolls of 18inch nominal diameter and two applicator rolls of 48 inch nominal diameter. The arrangement of these rolls was as shown in the General Arrangement Drawing included in the previous submission. The end two transfer rolls at at both the upper and lower level held the coating reservoirs which fed via the transfer rolls the two applicator rolls. In 1970 a high speed off-machine coating machine (OMCO) was installed as a means of increasing the production capacity of the two paper machines as these machines had the potential to run at a faster speed if the their on-machine coating section was eliminated.

A further product of SPM was Astralux which was produced on a dedicated specialist machine. The process was licensed from S. D. Warren of Maine, America and consisted of wet coating a paper-card which was then dried against a highly polished large diameter chrome cylinder to produce a card with a high-gloss surface, used mainly for product packaging. The base card was bought in reel form from an outside source but the finished product was usually sold in cut-sheet form.

4) PAPER FINISHING

The finishing process involved the use of various machines – supercalenders, slitters, cutters and guillotines

Supercalenders.

Where the paper web was passed between a vertical stack of soft and hard rollers in order to improve the surface finish for printing purposes.

The compressed cotton filled Supercalender (S/c) rolls were easily damaged by foreign objects passing between the rolls and thus they required frequent removal for regrinding. Eventually they would need refilling and this was done by either a Company in nearby Bolton, Richard Hough Ltd. or Middleton Ltd. The large diameter heavy steel roll (20 ton for No2 S/c) at the bottom-of-the-stack also needed periodic surface regrinding with a slight surface camber in order to compensate for its own deflection under operating conditions. As a high degree of precision was needed for this task, a specialised Voith roll-grinding machine had been installed in the Mill for this purpose. This grinding machine was also used for regrinding surface damaged or worn cotton-filled calender rolls and the rubber covered coating rolls. Periodic recovering was also needed for the rubber covered rolls and two suppliers were used, namely BTR Co, Ltd. and Moseley Rubber Co.

Reeling/slitting machines.

Where the wide webs were slit into narrower widths and/or smaller reels of paper.

Cutters.

Where reels were cut into sheets.

An innovation during the 1961/70 period was the installation of a Strecker Bruderhaus reel-to-sheet cutter in 1965/66 which was fitted with automatic sheet defect detection and sheet sorting equipment supplied by S D Warren (SDW0 of Maine, USA. The machine was named the Automatic Finishing Machine (AFM) and was basically a paper cutting machine turning paper reels of up to 65 inch width into paper sheets The AFM could accommodate two paper reels simultaneously. The operating speed of the AFM depended on the weight of the paper being cut, up to 1000ft/min, for long, heavy sheets falling to 500ft/min. for short, light sheets, the speed being governed by a limit on the rotational speed of the cross-cut knife(s). The cross cutter roll could be fitted with either one or two knifes depending on sheet length required. The maximum sheet length using two knifes was 42.75in. and the minimum 20in. With a single knife the maximum sheet length was 85in. and the minimum 42in. The AFM was also capable of slitting the paper width into narrower sheets.

The devices supplied by SDW consisted of a void detector and a bump detector and the necessary control system. The void detector had a minimum size hole resolution of 0.03 inch and the bump detector a minimum protrusion resolution of 0.0003 inch. Holes and bumps in the paper surface were potential press-stoppers for customers using the sheets, so SPM had an incentive to reduce these types of fault to a minimum. Having detected a fault, the control system operated a gate in the paper-run which directed the faulty sheets to a reject pile. (see AFM arrangement drawing in previous submission) The AFM also had a sheet counter and ticket insertion system for the accepted paper stack. All these quality control functions performed by the AFM had previously been carried out manually by the inspection staff.

Guillotines.

Where the edges of stacked paper sheets were trimmed, or, stacks were divided into smaller sheets

Inspection, packaging, warehouse and despatch.

The final sheet inspection area (The Salle) was a large area requiring a large number of people. It was mostly a manual operation, including the counting of sheets into reams and packaging them in protectiove wrapping. The large, heavy stacks of paper sheets were moved around on pallets using walk-alongside hand-controlled forklift trolleys, some power driven, others manually pulled. The final movement of the packaged paper reams into the warehouse tended to be by operator-ride-on fork lift truck as the warehouse paper stacks were stored on steel framed racks, multiple pallets high.. Similarly these same forklift trucks were used to move the packed paper stacks from the warehouse onto the transportation lorries in the adjoining despatch bays.

 

Note:

Some corrections and additions to the previous submission.

The Chief Design Engineer was Mr Harry Bassett

An earlier Chief Engineer to those already listed was Mr Albert Berry

In addition to the departments listed, there was also, a Quality Control department (including Laboratory testing of production processes and the finished product), a Medical facility with resident qualified staff, a Purchasing department, an Accounts department, a Personnel department, a Wages department and a Sales department. In total there was about 600 employees at the Feniscowles Mill.