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Manufacture of Safety Razors and Blades (1938)

Now we visit the Gillette factory in England on the cusp of WWII, courtesy of Machinery and Production Engineering (London), vol. 53 no. 1357 (1938, p33-38). Since 1927 production has moved from Slough to Isleworth. This happened very recently, ca. 1937. The razors produced are no longer the New Improved and Old Type, but the NEW. The working day appears to be 15 minutes shorter. The factory at Isleworth also produces blades, instead of importing them from Canada as in 1927.

Speaking of blades, compare the process here with that in 1956, still in Isleworth. They seem very similar — but soon after 1956 everything would change. First would be the Super Blue Blade, and then serious competition from coated stainless blades ca. 1962. In this 1938 article there is a brief mention of stainless too, but these would have been uncoated blades, probably like the KroMan in the USA.

I found the process for making NEW caps and guards illuminating. From descriptions in the Tech patent I thought die-swaging might be involved, and that appears to be true for the cap. It makes sense to include the lugs too, but I did not think of including the screw in that step. The guards were extruded in "the approximate cross section". That surprised me: I thought they were die-swaged too, or maybe cast. The teeth were sawn out, which fits with marks I have noticed. If the same process was used in Boston then this has implications for the 15-mm and 17-mm NEW Deluxe variants.

There is always a risk of inaccuracies, so use your critical thinking skills. I apologize for any typos and for the lack of illustrations, but there is a list of captions at the end.


The Manufacture of Safety Razors and Blades

Intensive Production Methods at the Isleworth Factory of Gillette Industries, Ltd.

The factory of Gillette Industries, Ltd., at Isleworth, is a familiar landmark to users of the Great West Road, and with its 500 feet long facade and its tower, 150 feet high, provides ample demonstration, if such be necessary in these days, that a factory building can be quite as attractive architecturally as a modern city building. Inside, the factory is no less interesting, and the visitor is at once struck by the general cleanliness which prevails, and the care which is taken in all departments to ensure comfortable working conditions for the operatives.

The output capacity of the factory is some 25,000 safety razors per day, together with as many as 1,500,000 blades, and this output is achieved with approximately 1,000 employees. In addition to Gillette safety razors and blades, the products of the factory include "Valet Autostrop" razors and blades, together with various other designs of blades which are sold under the names of "Probak," "7 o'clock," "Nacet," etc.

A week of 41 1/4 hours is worked in all sections of the factory, this comprising five working days of 8 1/4 hours each. The majority of the tools, and many of the special machines required in the factory are made in the tool-room, which is one of the most departments in the organization.

The Manufacture of Blades

Some of the most interesting plant installed in the factory is used in connection with the manufacture of blades. The blades are not made singly but are produced end-to-end in one long ribbon of steel, the parting-off operation being actually the last performed before final inspection, and being done after hardening, sharpening, and stropping. We may consider here the manufacture of safety blades of the Gillette type. These are made in a variety of designs to suit razors of different patterns, and are usually produced from 1.25 percent carbon steel which includes about 0.3 per cent of chromium. As is well known, ineffective drying of a blade after shaving is the chief cause of the edges losing their keenness. When moisture is allowed to remain on the edges, corrosion sets in very rapidly, with the result that the initial sharpness of the blade is soon destroyed. To offset this, a special brand of Gillette blade is made from stainless steel, and with these blades drying after shaving is unnecessary. Generally speaking a stainless steel blade may be expected to retain the keenness of its edges for a much longer period than a blade of ordinary steel.

Coils of blank strip are received at the works stores, the average weight of a coil being about 33 lb., and each pound of strip material will produce approximately 400 blades. The thickness of the strip for Gillette type blades is 0.0061-inch, and the tolerance permitted is plus or minus 0.0002-inch. In that case of Valet blades the strip is norminally 0.010-inch thick, the tolerance in this case being plus or minus 0.0003-inch.

The first operation on the steel strip consists of blanking and perforating, and is done on high-speed presses. One of the presses, with the rolls through which the material passes after leaving the press, is shown in Fig. 1. The strip passes to the dies through guide rollers, and two blades are formed at each stroke, the output from each press being 500 blades per minute. The rolls at A are used to flatten the strip after the press operation.

It will be noted that they are loaded by means of the weight B, and a system of levers, and the strip, after leaving the rolls, is coiled automatically on the drum C. The rolls remove any burrs or slight distortions which may have been caused by the presses. Simple combination press tools are used for perforating the strip, and the waste material falls through holes in the base of the dies to a suitable receptacle. Fig. 2 shows the form of the strip after it leaves the press.

After coiling, following blanking and rolling, the strip is treated in an Imperial Chemical Industries trichlorethylene degreaser, to remove all traces of oil and dirt. Four coils are operated upon simultaneously in the same machine, the material passing through the treatment chamber and being re-coiled again automatically following the actual cleaning part of the operation.

Hardening and Tempering

Particular interest attaches to the operation of hardening and tempering the strip after the degreasing process. The heat-treatment is done in electrically-operated furnaces, the hardening and tempering furnaces being placed end to end, so that after the strip passes through the hardening furnace, it is quenched and then passed directly into the tempering furnace. A reducing atmosphere is provided in the hardening and tempering furnaces to prevent oxidation.

One of the furnace lines is shown in Fig. 3. The formed strip is drawn from the coil by rolls, and passes first through the hardening furnace A, the temperature of which is maintained automatically. Leaving the hardening furnace the strip passes through water-cooled metal quenching boxes at B.

The tempering furnace at C is also electrically heated, the temperature being automatically controlled to within a few degrees of that specified for the treatment.

An interesting item of the heat-treatment equipment is the end tempering furnace at D. While the edges of the blades are tempered to give the most suitable results for shaving, the centres at X, Fig. 2, are of a somewhat different temper, to ensure the flexibility essential to prevent breakage when the blade takes up its correct curve as held in the razor. In the end tempering furnace, therefore, the strip passes between copper terminals, and current is thus passed continually along that portion which is between them. This current does not affect the edges of the blades, but it heats up the centre portions, which will later form the ends of the blades, and in this way provides additional tempering. [footnote: British Patent No. 401366, or GB401366A, application 1932.]

In the case of "Blue Gillette” blades, the characteristic blue colour is imparted to the material by the provision of a special gas mixture in the hardening furnace. Depending upon the material concerned, the speed of the strip when passing through the line of furnaces varies between 250 and 350 blades per minute. On leaving the end-tempering furnace, the strip passes between a pair of pull-through rolls, and is then coiled on the drum E, Fig. 3.

Marking and Lacquering

Acid-etching machines are used to mark the safety blades with the trade-mark and other lettering. The coil is fed to the printing device by rolls, and the inscription is printed on the blades by rubber stamps, each being of sufficient length to print two blades on both sides simultaneously. In operation, the rubber stamps first rest on fabric pads, which are level with the strip, and then move over to print the blades. The machine operates very rapidly, and actually stamps and etches 400 blades per minute.

Leaving the printing device, the strip passes through a neutralizing bath of alkaline solution, which kills the acid, and then moves between air jets, which blow upon it to remove the liquid. Next, the strip passes through a heating chamber, which dries it thoroughly, and finally between two rotating mops, which wipe it on both sides before it is coiled ready for the lacquering operation.

One of the sets of lacquering equipment is shown in Fig. 4. This, as will be seen from the illustration, accommodates six coils of printed strip material simultaneously. The strip is drawn from the coils A, over rollers, and down into the lacquer bath at B. Leaving the bath, the steel is passed upwards through the preheating oven C. It then passes to the stoving oven D, through which it travels before being wound again on the coils at E.

The speed of the strip on its way through the bath and ovens is 80 blades per minute for each of the six coils. The pre-heating oven, and the stoving oven, are both electrically-heated, the actual temperatures being controlled automatically.

Before the grinding, honing, and stropping operations on the strip, several coils of standard size are spot-welded together to form one large coil. This avoids any unnecessary reloading and re-setting of the machines, and at the same time affords an opportunity of inspecting the blade strip for cracks and other flaws. An automatic machine is employed through which the strip is passed at high speed. When a flaw or a crack is encountered, the machine stops automatically, while a red light warns the operator that something is wrong. The defective section is then cut from the band, and the two ends are joined together by welding. In the same way, when the end of the blade band is reached, the machine stops automatically to enable the operator to weld the end of the next coil to it.

Specially designed machines are used for grinding, honing, and stropping, these three operations being done on what is virtually one long machine. One of these complete machines is shown in Fig. 5, the machine being seen from the starting end.

The coil is placed on a horizontal table A, and is drawn through the machine across the various grinding and honing wheels with the cutting edges of the strip in the same vertical plane. Each individual blade passes through the entire sequence of sharpening operations in about 30 seconds. The first two of the units in the line provide for grinding the rough angles on the edge of the blades, each of the two units grinding one upper and one lower edge. The next unit bevels the angles, a finer grade of wheel being used for this operation, after which the strip passes through the various honing units, which carry wheels of still finer grade. Stropping is done by means of leather wheels about 1/4-inch wide, several of these being mounted on a single spindle with spacing collars between them.

At the end of the machine, after leaving the stropping wheels, the blades are cut off one by one at very high speed. The cutting-off station is shown in Fig. 6.

The band is indexed to the cropping shears by the crank at A and a connecting rod and slide, location being taken from the holes pierced in the centres of the blades. A slide B, operating at right angles to the direction of travel of the strip, holds the cropping tool, and the parted-off blades are stacked on to the pins C of a holder or carrier.

The holder seen in position on the machine in the illustration is about half full, a quantity of finished blades being seen at D. A completely loaded holder is shown at E, while an empty holder is seen at F. Each holder accommodates about 900 blades. Normally, cutting-off is done at the rate of 350 blades per minute. The loaded holders are inspected as they are taken from the sharpening machine, and any defective blades are removed. Special mercury vapour lamps are used to illuminate the benches where these charged holders are inspected, and blades which are not sharpened properly reflect light differently from satisfactorily sharpened blades when the charger is held at certain angles, and can thus be readily detected. Various blades are selected for individual testing, and are checked with precision measuring instruments. In any blade, the two edges must be at a certain distance from the centre line, and the maximum tolerance for this distance for each of the two edges is not more than 0.002-inch, while the tolerance for the overall dimension of the distance between the two cutting edges is ± 0.004-inch. One of the inspection tables is shown in Fig. 7.

Wrapping and Packing

Special machines are installed for wrapping and packing the finished blades. Each blade has an outer printed wrapper, and an inner waxed paper wrapper which prevents moisture from reaching it. One of the automatic wrapping machines, which is capable of wrapping as many as 40,000 blades per day, is shown in Fig. 8. The printed outer wrappers are held in a cage at A, while the waxed paper is drawn from a coil at B. The stack of blades to be wrapped is seen at C. In the first place, the printed wrapper is drawn from the magazine and placed in a pocket on the table.

As the table rotates, the waxed paper is cut from the roll by a shaped knife, and is placed on the printed wrapper ready to be folded round the blade. As the table rotates still further, the blade is slipped from the lower end of the charger and placed in position on the two wrappers, and the metal fingers then close the wrappers over on to the blade. These fingers work in pairs, the waxed paper being first closed over the blade before the outer wrapper is folded into position. At the last station, the package is pushed by a plunger into the vertical guide tube D, from which batches of the wrapped blades are taken as they accumulate.

The packing of wrapped blades into cartons of five, six, or ten, is also carried out by automatic machines. Batches of paper are placed in a number of vertical channels, and from the channels are fed in batches of five, six, or ten to pockets in an endless chain which moves along the front of the machine. The cartons are fed into pockets of a second endless chain which runs parallel to the first chain, and during their travel are opened ready to receive the blades.

At one point the blades are traversed into the cartons by means of a simple finger movement, and the loaded packets then move on further mechanical fingers sealing them before they reach the table, where they are checked and finally wrapped automatically in cellophane paper to exclude damp. Special interconnected devices are used on the packing machines, which reject any packet that does not contain the requisite number of blades.

The Manufacture of Razors

One of the most popular razors manufactured by Gillette Industries, Ltd., is the 3-piece type, which comprises a handle, a cap, and a guard. The handle is actually made up of three parts, these being the central tubular portion, the end knob, and the neck portion which joins the tubular part to the guard. Brown & Sharpe automatics are used to produce the handle components and generally the methods now used are very similar to those described in an article which appeared in MACHINERY, 31/97—-27/l0/27. Arrangements are, however now made to ensure large-scale production to meet the increased demands on the factory.

The caps are machined from hot brass pressings, the caps being solid, and the extension for the central screw and the locating lugs being formed by the dies. After trimming the pressings to size, the first machining operation consists of screwing the centre pin, and the work is then ready for the operation of form-milling the tops.

Fig. 9 shows the method of holding the work for the form-milling operation. The machine illustrated is a Werner horizontal-spindle milling machine, which was supplied by E. H. Jones (Machine Tools), Ltd., but Brown & Sharpe machines (Buck & Hickman, Ltd.) are also employed. Three form-milling cutters are carried by the horizontal arbor of the machine, the work-pieces being arranged in three rows on a special fixture mounted on the table. Location is taken from the centre pin and the ribs on the underside of the component, and clamping is effected by the three screws A. The set-up illustrated provides for milling 27 caps at a single setting, but in other cases the work-pieces are arranged in four rows, and four milling cutters are employed, enabling 36 caps to be dealt with simultaneously.

The remaining operations on the cap are of a simple character, and do not call for detailed description. They consist mainly of polishing and plating, and this work is carried out on orthodox lines.

Operations on the Guard

The guard is machined from an extruded brass strip of the approximate cross-section, the material being of approximately 66/33 composition. An interesting method for slitting the material to length has been developed by the Gillette works, and the machine employed for this operation is shown in Fig. 10. The machine consists essentially of a rotating drum, grooved longitudinally on the periphery to receive the stock A, which is held in position by curved spring clamps.

The stock passes under a gang of saws carried on a horizontal arbor, so that all the pieces are cut from each strip simultaneously. Lateral grooves in the surface of the drum provide the necessary clearance for the saws. The output from this machine is as many as 10,000 pieces per hour.

Another interesting machine made in the factory is used to cut the teeth in the guard, and is shown in Fig. 11. The machine provides for bringing the guard blanks into contact with two gangs of cutters which cut the teeth on either side of the blank simultaneously. The two horizontal arbors, each carrying twelve saw cutters, are enclosed, and are geared together. Collars separate the various cutters on the two arbors, the cutters being about 2 1/2 inches in diameter, and revolving at a speed of 2,400 rpm.

In operation the work-piece A is located by a pin which engages the centre hole, and by ridges which engage the axial slits. As the ram C rides upwards to the saws the work is gripped by the two hook clamps B and is thus held in position by spring tension. Two small rods pass through the ram and project from the face of the work-locating pad when the ram is at the bottom of its stroke, thus serving to eject the work, which drops down the chute D in the ram. A production rate of 1,000 pieces per hour is obtained from the machine. The operator uses a pair of tongs to handle the work-pieces, as shown.

Trimming Drawn Brass Boxes

Fig. 12 shows an interesting press operation, which provides for the trimming of drawn brass boxes for safety razors. An untrimmed box is seen at A and a trimmed box at B, while in position between the dies of the press is a trimmed box together with the material removed.

The ram of the press carries the upper shearing tool C, and four end-locating plugs D which engage the lower shearing tool E when the ram is in the down position. Mounted on the face of the upper tool is a spring-loaded bolster pad F, which is free to move on the face of the tool, but which is normally held with its edges flush with the sides of the tool by spring tension. As the ram descends, the bolster locates inside the box and the stop pieces D engage the lower die, which is spring-loaded, so that the upper die is located vertically in relation to the lower die. The actual box rests on a spring-loaded base, and is pushed into the lower die by the bolster. . The base holding the lower die is then given both sideways and forwards and backwards movement, so that the upper die presses into each corner and is pushed into the lower die by the bolster.

The base holding the lower die is then given both sideways and forwards and backwards movement, so that the upper die presses into each corner of the box in turn, shearing off the waste material. It will be noted that the component is placed diagonally in the die, so that the shearing action resulting from the two movements of the compound slide takes place at the corners of the box rather than at right angles to the sides.

List of Figures

  • Fig. 1. One of the Automatic Presses for Blanking the Strip Material for Safety Blades
  • Fig. 2 The Form of the Strip Material as it leaves the Blanking Press
  • Fig. 3. One of the Lines of Hardening and Tempering.
  • Fig. 4. Equipment for Lacquering the Strip Material for Safety Blades
  • Fig. 5. One of the Continuous Blade Grinding, Honing, and Stropping Machines
  • Fig. 6. The Blade-shearing Station at the End of the Grinding, Honing, and Stropping Machine
  • Fig. 7. One of the Blade Inspection Benches
  • Fig. 8. Special Machine for Wrapping Safety Blades
  • Fig. 9. Gang Milling Set-up for Razor Caps
  • Fig. 10. Special Barrel-type Machine for Cutting Guard Material to Length
  • Fig. 11. Gang Milling Machine, for Cutting the 24 Grooves in the Guard Simultaneously
  • Fig. 12. Set-up for Trimming Safety Razor Boxes of Drawn Brass Sheet Material
 
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