The commutator production and assembling job
The ford commutator consists of a case, contacts, and rotor fixed to the end of the cam-shaft, geared to make one turn to two turns of the motor crank-shaft.
This rotor hub, T-4446 (see the plate on page 218, showing rotor components , fiber insulation ring and hand-nuts) has two short parallel arms on one side, forming a clevis, adapted to have pivoted therein a swinging arm, T-672, this T-672 having also two arms forming a second clevis adapted to take the hardened tool-steel pin, T-476, and hardened tool-steel roller, T-673, extending from one side and a spring-tail extending from the other side.
The rotor hub, T-4446, has also a spring tail extending in an opposite direction to the clevis arms, and a close-wound, coiled, steel-wire spring, T-469, has its ends hooked into the two spring tails specified, all so that the spring tension constantly tends to swing the hard-steel contact roller, T-673, away from the hub of the rotor, T-4446, as the rotor revolves with the cam-shaft.
The rotor is surrounded by a vulcanized-fiber insulating ring, T-4447, forced into the case, T-4439, page 219, and afterward milled with four sinking cuts, to take four contact assemblies, T-462-B, with their hand nuts, 90 degrees apart, all as shown in two views, symbol T-4443, on page 219.
The commutator case is revolubly seated on its large end concentric with the cam-shaft, placed to make the four contact-head faces match the rotor roller for height, so that as the rotor revolves the roller will contact with the four fields successively.
The four contacts are wired to four coil boxes, each coil being wired to the fly-wheel magneto so as to be supplied with electric current so long as the motor fly-wheel revolved at 25 or more turns per minute; but as the contacts are insulated in the fiber ring pressed into the case, there can be no ignition-spark-creating discharge of electric current until the rotor roller touches a contact and so grounds the electrical circuit.
The case can be rocked by its integral control-rod arm, so as to cause the contact to occur earlier or later in the rotor revolution, thus advancing or retarding the ignition-spark production time.
A constant spring pressure is maintained on the small end of the case to hold the case to its seat. In the illustration on page 219 an oiler is shown seated opposite the case control-arm, which placing of the oiler makes the case right-hand control. If the oiler is moved round 180 degrees, and seated in the center and hub there placed, next to the control-arm, then the case is left-hand control.
The outside diameter of the finished case is 3 inches, inside diameter 2 13/16 inches, total height 2 inches, and the weight of the case aluminum casting, rough, is 4 1/2 ounces.
The weight of the complete case assembly T-4443, is 6 1/4 ounces. The weight of the complete rotor assembly, T-4481, is 3 ounces. The combined weight of the case assembly and the rotor assembly is 9 1/4 ounces. The retail selling price of the commutator, case and rotor complete, is $1.50.
Sixty men, total, produce 1,750 of these Model T commutator and rotor assemblies in one 8-hour day, 480 hours total, a production of one Model T complete commutator for something less than I6V2 minutes of one man's time, as against 24 minutes 18 seconds, Jan. 11, 1914, before the commutator job was first moved to the fourth floor, and of 23 minutes 41 seconds of one man's time per commutator completed, March 31,1914, after the commutator job was moved to the fourth floor and before the casefoundry was installed there.
The commutator job is such as to make the best relative placing of the machine tools and benches a matter for trial after the job was moved to the fourth floor, and the placing of the work-slides was not completed March 31; hence the small labor-time reduction shown from Jan. 11 to March 31,1914. Now, August 12, 1914, everything except the brass castings for the rotor is in pretty fair form. These brass castings were made outside, the Ford shops having made their first brass casting Aug. 10, 1914, and a hand-hammer operation is required on the rotor-hub spring-tail. The Ford shops are now making new pat terns for the rotor brass castings which will bring them right, and will somewhat lower the present labor-time of I6V2 minutes of one man's time for each commutator produced.
The sixty men on the commutator job are divided as follows: One head, one foreman, two tool-setters, one straw-boss, one clerk, three men in the screw-machine department, one of whom hardens and tempers the tool-steel rollers and roller-pins, and three hands in the foundry.
The workmen's routine for shop entering is: ring up on time clock, take work card from clerk's desk, go to tool crib, take out tools, leaving checks at tool crib, remove street clothing, and be at their places ready to work at bell time 6:30 a. m.; lunch, 10:30 to 11:00 a. m.; start at 11:00 a. m. and work until bell time, 3:00 p. m. After the 3:00 p. m. bell, each worker cleans his machine, then fills his production card, and on his way with his tools to the tool crib leaves his production card at the clerk's desk, and then leaves his tools at the tool crib and gets his checks back again.
Checking all tools into the tool crib at quitting time makes it certain that all tools will be ready for the workmen at starting time next morning , or for the workmen in the following shift. Each workman takes his production card from the clerk's desk at starting, when he obtains his tools from the tool crib, the clerk's desk and the tool-crib window being close together.
The form-blanks used in the commutator department are the workmen 's time card, the non-productive time ticket, Form 759, the productive time ticket, Form 915, and the report of stock machined, Form 552, all of which, with their uses, have been already shown and described.
Roller and Pin Hardening
The contact rollers, T-673, and their pins, T-675, are of tool-steel, and are hardened by being heated to 1,400 degrees F., quenching in a caustic-soda bath, and are tempered in a bath of Atlantic tempering oil, kept at a temperature of 400 degrees F.
The pins and roller holes are not ground. The rollers are placed on an arbor and ground to uniform diameter. The commutator life is about five years, ordinary car-duty; hence, as there are now over 500,000 Model T cars in use, the commutator replacements are over 100,000 per year, and the replacement requirements are constantly increasing.
The vulcanized-fiber insulation is of the yellow-gray variety, which is much stronger than the red-colored sort, and is very hard on cuttingtool edges.
Special Machine-Tool Constructions
The only unusual special machine-tool adjunct used on the commutator job is a drilling-machine spindle addition, Ford design, carrying three drilling spindles, for drilling T-4446 and T-672, all three holes at one time.
These are of ordinary forms, leaf and stationary bushes. The great number of illustrations given with this commutator story, together with the brief description of the commutator itself, will give the reader a fair idea of the Ford commutator department.
Ford engineers are fully aware that the lowest costs cannot be had save by placing all the tools and men used in one assembled-component production close together and in operation sequence, so that each component shall have the shortest possible line of travel, with the fewest handlings.
Placing a Foundry in the Machine Shop
To carry out fully the foregoing proposition!the aluminum foundry for producing the commutator case T-4439, is placed at the north end of the commutator machine-tool floor. The watchman starts the aluminum -melting furnace gas-fire at 5:00 a. m., and thus makes the metal ready to pour at 6:30 a. m., starting time. Three men, two machine moulders and one pourer, shake-out, and furnace man, produce the rough casting aluminum cases, hour by hour, as they are required by the finishers, about 1,800 per 8-hour day, maximum.
We are so thoroughly accustomed to the entire separation of the machine shop and the foundry that most shop men have never given a moment's thought to the advantages gained by making the foundry a part of the finishing floor, even when using a low-heat-melting metal.
In the present case there is no requisition made for case castings, and no handling and transportation of case castings between the foundry and the stores room,nor between the stores room and the commutator department. No writing, nor records needed, save weight of pig melted.
The case castings are simply in the boxes, ready to hand, as if they grew there or blew in at the window . No one has to pay any attention to the roughcase supply, because the supply begin s automatically when the starting bell rings and continues until the quitting bell rings; every hour so many cases moulded , knocked off the gates, and placed in the boxes ready for snagging.
In a word, the commutator-case production starts at 100 per cent efficiency, an impossible condition if the case-foundry were not placed where it is, on the machine-shop floor, where it forms the first element of the commutator-production plant, as it should and must, if 100 per cent efficiency is to be made possible.
See views on page 220, aluminum foundry on machine-shop floor, for producing the commutator case, T-4439. The small moulding floor has a shake-out grating, not shown here, inside the concrete low wall which separates the moulding floor from the machine-shop floor. The
founding equipment includes two Berkshire Manufacturing Company 's Model E moulding machines , with match plates for the cope in one machine and for the drag in the other machine, followboards and flasks, and one moulder to each moulding machine.
The aluminum-melting furnace is housed in the small room at the left, with open door, as seen at left extreme. The furnace is of Ford construction and is attended by the workman at the left, who also pours the moulds and shakes out
the work, ten cases, T-4439, to each flask, and knocks the cases off the runner with a mallet as seen in picture. Time required to put up the cope, 1 minute 33 seconds, drag 1 minute 42 seconds.
These three men, two moulders and one helper, turn out about 1,800 cases,T-4439, per 8-hour day. The picture on page 220 shows the aluminum-melting furnace, "Industrial" construction; capacity about 200 pounds of aluminum alloy. The furnace is gasfired , and gives metal ready for pouring in about 80 minutes after the burners are lighted.
Snagging Cases, T-4439 The photograph on page 221 shows at the right a workman at an emery wheel, snagging cases, T-4439; time of snagging, 4 seconds ; front, right, and left, boxes of cases. Two annealing chests, partly filled with gray-iron chips, the chests having hinged covers, all of sheet iron, show at the middle left, with annealing furnace and chain hoist above. This view is at the north end of commutator machine floor, on which tools are placed for commutator finishing in operation sequence.
The progressive finishing operations upon the cases and other components making up the complete commutator assembly are given in the following pages in a condensed description which covers the main points of the nature of each job, the machine or tool used, the time taken, and any points of special interest attaching to the work or the equipment used. The illustrations follow in close parallel to the text and are referred to by number as the point they show particularly is taken up.
- Finishing the Commutator Case, T-4439
- Operation 1. Bore inside diameter and face: chuck and bore on two Warner and Swasey turret machines, two men. Time 19 seconds. The times here given are stop-watch from actual operation time of workmen. The pictures are flash, actual work, no posing.
- Operation 2. Turn outside diameter and center. Page 223, two Reed and Prentice lathes, two men. Time on one case, 18 seconds.
- Operation 3. Drill one u/32 hole, time 6 seconds. One Allen drill press, one spindle, one man.
- Operation 4. Punch one 15/64 hole, time 3 seconds. Ferracute press.
- Operation 5. Tap 11/32 hole, 1/2 pipe tap, for oiler; Garvin tapping machine; time 7 seconds.
- Operation 6. Makes the case ready to have the fiber insulating ring, T-4447, forced into its inside.
Machining the Fiber Ring, T-4447
Operation 1. Bore out inside. One Warner and Swasey turret machine , one man, time 11 seconds. Operation 2. Turn outside, 1 Warner and Swasey turret machine , one man, time, 10 seconds.
Machining the Contact Head, T-4462
The contact head is cut, ten pieces at once, from a bar of crescent -section steel, with a gang of mills in a Pratt and Whitney hand milling machine. The time required to cut ten pieces from the bar is 53 seconds. One machine, one man. See page 224. This constitutes operation 1.
Operation 2. Tumble, Ford tumbler.
Operation 3. Drill one No. 19 hole in middle of contact head, Langelier Manufacturing Company's special driller. This driller has a spindle head, carrying ten vertical spindles and revolving at constant speed on a vertical axis. The work is automatically fed up to the drill-spindles.
This is an elaborate semi-automatic machine-tool, rapid and precise in action.
The contact heads are placed by hand on a horizontal, revolving circular table, flanged at the edge, against the flange. Then an automatic finger pushes each head-blank into a receiver in the bottom part of the revolving drill head, and the heads are drilled and ejected as the drill head revolves. See page 225. One man and one machine drill ten contact heads in 18 seconds.
Operation 4. Tap holes in contact heads, T-4462. One Barnes drill press with one man, and one Allen drill press with one man; long-shank taps in drill spindles, taps 10-32; taps are rim through until the shank length is filled with contact heads, then the chuck is released and shank cleared of heads. One man taps six contact heads in 33 seconds.
Commutator Contact Stud, T-4471
Operation 1. Thread both ends and cut off. Brown and Sharpe automatic screw machine, single-spindle, as shown on page 226; also, same piece, T-4471, on Acme four-spindle screw machine, no illustration.
Time, one stud, Brown and Sharpe machine, 10 seconds. Acme fourspindle machine, 6 seconds.
T-462-B Assemble Contact Head, T-4462 and Stud, T-4471
Operation 1. Assemble head and stud, Ford machine in middle, one spindle, constant speed, with friction driven "Gronkvist" automatic chuck. While the chuck is running, a stud is slipped into the chuck, which automatically tightens when the head is held in hand pliers by the man at the right, and applied to running stud, held in the frictiondriven , self-tightening chuck. This screws the stud, T-4471, into the contact head, T-4462, as far as the friction will drive it. The workman then grasps the chuck-shell, which releases the stud, and the workman then drops the assembly into a tray on the bench. Time for 10 assemblies, 48 seconds (man at the right). The workman at the left takes the assembly from the tray, grasps the stud in a vise, and with hand brace turns the head down hard on the stud. Man at left keeps pace with man at right. Two men complete assembly of ten pieces, T-462-B, in 48 seconds.
The "Gronkvist" automatic drill chuck is extremely rapid and convenient in action, is self-tightening, and is made to release with very small muscular exertion.
With a production of 1,750 commutators in 8 hours, 7,000 of these contact head and stud assemblies are used in 8 hours, and speedy production of this T-462-B assembly is highly important. At first the T462 -B assembly was made an integral drop-forging, and the stem was milled with a cup-mouth mill, which also shaped the convex side of the contact head; this method had the fault of leaving the outside of the head curved, which made it needful to cut the contact seat in the insulation ring, T-4447, with a curved-face mill, and these objectionable features led to the present satisfactory construction with the head and stud separated, screwing them together, then electric welding the stud to the head, and finally annealing the assembly because the electric welding produces hard spots.
Operation 2. Electric weld T-462-B. One man, Winfield Electric Welding Machine Company's welding machine. Time, 3 seconds. See page 228.
Operation 3. Anneal T-462-B. 5,000 components T-462-B are packed for annealing as follows: the annealing boxes are of gray-iron with covers, as shown on this page. A rough tray of sheet iron, about half an inch smaller all round than the inside of the box, corners merely cut out and sides and ends folded up, is provided to hold, say, 5,000 contact assemblies. Half an inch of gray-iron fine chips is spread over the annealing box bottom, then the sheet-iron inside tray is set on the chips, the 5,000 assemblies are put in, and then the whole inside is packed with gray-iron chips, the box cover is laid on and luted with fireclay , and the box is placed in the "Industrial" furnace, cold, and the gas fire turned on, heating everything gradually for from 2 to 4 hours, until the pyrometer shows 1,600 degrees F. Then the box is withdrawn from the furnace and buried in gray-iron chips in one of the large sheet-iron cooling chests, where it is let lie for 24 hours, at the end of which time
the box is cool enough to handle. The labor time charged against these 5,000 pieces of annealing is 30 minutes of one man's time, for packing in annealing box.
L. H. Commutator Case Assembly, T-4443, Operation List
Operation 1. Press fiber ring, T-4447, into case, T-4439, by use of one No. 3 Grenerd arbor press, one man, time 7 seconds.
See picture adjoining. Operation 2. Mill four sinking cuts in the fiber ring for seating contact heads, drill for four contact studs, and counterbore for four stud insulations, T-671, page 218. Contact heads seated 90 degrees apart in ring; two Pratt and Whitney hand milling machines and two men. Time for one case, 1 man, 26 seconds.
Two belt-driven drilling and counterboring spindles are journaled in this fixture, in the plane of the mining machine spindle, and the central part of the fixture frame is bored to take the round fixture in which the case assembly is fixed; the round fixture is revolubly seated and can be hand-indexed in two positions, 90 degrees apart. The milling-machine spindle carries a shank-mill, same radius as outside of the contact head.
Action. The case and fiber-ring assembly is clamped in the fixture, which is on a slide, and with the fixture indexed in one position the slide is moved both ways to stops, which cuts the contact-head seats and drills and counter-bores the case on two sides, 180 degrees apart. Then the fixture is indexed 90 degrees and the slide is again moved to the same stops, both ways; total time of one man and one machine for making the four contact cuts in one case, 26 seconds only.
Operation 3. Burr fiber ring and clean out contact stud holes, hand operation on bench, as shown on page 235. Time, 6 seconds. Operation 3 is performed by the middle man on the left side of the sheet-metalcovered bench, who drops the cases as burred and cleaned on the bench at his right front, convenient to the left hand of the first man on the right side of the bench, who performs Operation 4, placing a contact assembly (T-462-B) in each one of the case four contact seats, and then drops the cases at his right, ready to be picked up by the second man on the right-hand side of the bench, who performs Operation 5, placing four contact-stud insulating-fiber bushes (T-671) in their seats in the case, around the contact studs, and then drops the case on the bench at his right.
Next, Operation 6, the case is picked up by the man at the extreme left of the bench, who uses the Ford machine shown on page 235 for performing Operation 6, running a brass hex nut (T-472), on each one of the four contact studs. This Operation 6 machine has a belt-driven spindle carrying on its nose a friction-driven hex-nut socket, in which, while running, the operator places a hex nut, and then pushes a contact stud against the nut which is then friction-driven up against the fiber bushing.
After running nuts, Operation 6 workman drops the case on the bench from his left hand in front of the third man on the left of the bench, who performs Operation 7, tightening up each of the four contact-stud hex nuts, by hand, with a box hex-wrench, bringing the nuts to a good solid bearing on the fiber bush, T-671, and making sure that the contact head is fairly placed in its seat in the inside fiber ring, T-4447, and thus making the case ready for Operation 8.
The operation times are: Operation 3, 6 seconds; Operation 4, 10 seconds; Operation 5, 10 seconds; Operation 6, 12 seconds; and Operation 7, 11 seconds.
Operation 8, page 236. Bore out inside diameter; time, 64 seconds. Five Reed-Prentice engine lathes, with Ford hand-revolved and latched, four-tool, four-position turrets. Two lathes are shown on page 236. This operation takes a finishing cut to exact inside diameter over the fiber ring and contacts, and also on top and bottom of fiber ring and contacts. From these lathes the cases go first to the chip cleaner, shown at the right of the lower view on page 236, and then to the inspector, page 237. It is important that all boring chips be removed before testing, because of a possible current - circuit. The chip-cleaner stands near the tallstock end of the right-hand lathe.
Operation 9. Inspection of case, including insulation test. The inspector examines the case to see that it is free from chips, gauges the outside diameter, and places the case on an insulation test block, wired to a bank of four lamps, which light if insulation is defective. See page 237. One inspector only for each shift.
T-671 Commutator-Stud Insulation-Fiber Bush
Operation 1. Stock is gray fiber rods, 7i6 diameter by 68 inches long. The bushes, T-671, are made on two Warner and Swasey turret machines, two men, one operation time, 4 seconds. Page 238.
In ordinary screw-machine practice, the turret would carry one stop, to fix stock length out of the chuck, and one drill, to drill the bush-hole, and the cross-slide tool-post would carry a cutting-off tool, moved by the cross-slide screw, and the fiber bushes, when cut off, would drop down into the chips and have to be picked out by hand, somewhere about 7,000 of them for every 8-hour day's work.
Changes Made in T-671 Production Milling Machine The head of the commutator department at first made these fiber bushes, T-671, by the foregoing ordinary routine, but has since doubled.
The middle figure, at the tail-stock end of the right-hand lathe, is an inspector the per hour production by making the following list of changes. The cutting-off tool is shouldered on the head-stock side, so that by moving the cross-slide inward to a stop the small diameter of T-671 is made on the next bush about the same time a finished bush is cut off, in a well known manner.
See page 238. The cross-slide screw is taken out; an arm, 1, is fixed in the turret and has fixed to it the slot-piece down-hanger, 2; the slot takes a stud fixed in the cross-slide and projecting upward, the slot head-stock-end leading to front in the illustration, all so that as the turret slide is moved forward towards the headstock, the cross-slide is moved outward, away from the work.
The turret is locked to the slide and does not revolve at all. The turret stock-stop is chambered to be an easy fit on the small diameter of T-671, and also has fixed in it a twist drill projecting more than the total thickness of T-671 beyond the stock-stop flat face.
A thin sheet-brass spring is fixed to the top end of a stud projecting upward in front of the cross-slide tool-post, this spring being bent into a quarter circle at its inside end, all so that, as the finished bush is being cut off, the brass spring will press against the bush front side, and when the bush finally breaks off the spring snaps the bush against the flanged top-incline of sheet iron, seen above the work-catching box, top of page 238, so that the bush drops into the box, instead of dropping into the chips.
The cutting-off and shouldering tool of course raises some burrs on the work and on the stock, and it is common practice to remove these burrs with a hand-file, floatcut , a hand operation which uses both of the operator's hands and so takes considerable time, say IV2 or 2 seconds, to remove hands from levers, pick up the file, remove burrs with the file, lay the file down, and again grasp one lever with each hand.
In these T-671 producing machines , a spring-lifted file-block, double-ended, float file-cut top and bottom, is placed underneath the work, at 4, page 238, so as to hold the top file-cut surface constantly up against the under side of the stock and work and burr the job, so the operator need not take his hands off the levers. This fileblock is lifted by a very weak spring andhasalonglife; thosenow in use have worked for a year, one endonly,andtheteethareyetgood.
Both the flip-over spring and the spring-lifted, float-file-cut-block are new devices to the writer; the flip-over spring saves picking 7,000 bushers, one by one, out of the fiber chips every 8 hours, and the springlifted automatic, file burring-block saves 5 movements of each of the operator's hands for each one of the 7,000 pieces produced per 8-hour day, 35,000 movements of each hand of the workman per 8-hour day, 70,000 motions total: viz.:
Operation 9. Case Inspection, Showing Insulation Test Block The bank of lights glows when the ease is placed on the test block if the insulation is faulty; four lamps, one for each contact in the case (1) Take both hands off levers; (2) Pick up file in both hands; (3) With both hands file off burrs; (4) Lay file down; (5) Re-grasplevers,bothhands.
This little story of little things shows in a very striking manner the labor-cost-reducing value of seemingly insignificant minor inventions.
This is a device new to the writer, and applicable to any small piece of turret-machine work; it saves picking the 7,000 bushes out of the chips every 8 hours.
Because of moving the crossslide by the rigid slotted-bar fixed to the turret, the operator can keep his right hand constantly on one bar of the capstan which moves The changes made by the head of the commutator department doubled the production per hour of the two turret machines making the bush T-671 the turret slide; if the turret is moved away from the head-stock the cross-slide is moved inward; if the turret is moved toward the head-stock, the cross-slide is moved outward. The operator keeps his left hand constantly on the livespindle chuck-lever. The stock is ratchet-fed toward the turret in the usual manner.
Having cut off one T-671, the operator pulls the chuck-lever towards him and pushes the turretslide lever away from him, keeping the end of the stock against the stop drill-point, until the capstan lever stands about horizontal; then the operator moves the chucklever away from him, to grasp the stock lightly, and pulls the capstan lever until the turret-slide, moving towards the head-stock, reaches its stop, the hole in the next T-671 being drilled and the T-671 tit entering the stock-stop counterbore and the stock-stop flat end pushing hard on the next T-671, the crossslide meanwhile moving outward; when theturret-slide meets its stop, the workman pushes the chucklever away from him to full chucktightening position and holds it there while he pushes the capstan lever away to draw the turret back, the cross-slide and cutting-off tool meanwhile being moved inward by the slotted piece fixed to the turret and moved with the turret slide, until the cross-slide reaches its stop, cutting off the new T-671 and forming the tit on the next T-671, the brass spring flipping the new T-671 into the box as soon as it is cut off.
This novel scheme of turret machine and tools construction and handling permits the operator to keep one hand on the feed-andchuck lever and the other hand on the turret-slide capstan-lever, and to produce twice as many of T-671 per hour as by ordinary practice; and it also places the finished pieces in the box away from the chips, so that picking them out of the chips is avoided, and is here described at length as something new and extremely useful in turret -machine operation.
Commutator Rotor Body, T-4446
This piece is a brass casting. Operation 1. Straddle-mill ends on Pratt and Whitney hand milling machine; one man, time 5 seconds.
Operation 2. Two men on one Allen two-spindle driller, and two Allen single-spindle drillers, altogether three men, drill and ream large hole in the hub of rotor body, T-4446. Operation time, 30 seconds . See page 239.
Operation 3. Smooth and burr, Ford rotary files; float cut, on Ford machine. Makes fine brass dust; two men wearing nose protectors . Operation time, 15 seconds ; this page.
Operation 4. Ream to 9/16. Langelier driller; operation time, 7 seconds.
Operation 5. Cut Vs slot.
Pratt and Whitney hand milling machine; operation time, 9 seconds.
Operation 6. Drill l/ia hole in rotor spring-tail. Burke bench driller; operation time, 5 seconds.
Commutator Roller Clevis, T-672
This is a brass casting. Operation 1. Straddle mill. Pratt and Whitney hand milling machine; operation time, 7 onds. Page 240.
Operation 2. boss; operation time, 6 seconds Operations one and two are shown on page 240. Pratt and Whitney milling machine.
Operation 3. Drill two U/M holes, Ford special three-spindle head on one spindle of an Allen two-spindle drill press; operation time, 2 seconds. See page 240.
The two drillers, single spindle, at right, are Burke one-spindle drillers , set close together, so as to be used as a two-spindle machine, and are also used for operation 3. A Ford special three-spindle drilling head is shown at left, working, and at right, lying down on the drilltable . These special heads are made to carry three taper-shank drills each, drills % and U/M, center to center. This Ford special three-spindle drilling head is of interest, and a section and plan are shown in the construction drawing reproduced on this page, as likely to be of service to readers who can save time by placing the drill spindles very close together. The peculiar feature of this construction is the making of the intermediate gear long enough to cover both the driving and driven spindles, which gives the largest possible drill-spindle diameter for a given center-to-center distance.
Operation 4. Ream one 11/64 hole. Burke drill press; operation time, 2 seconds. Page 240.
Operation 5. Drill one hole, No. 32 drill, Burke drill press; opera' tion time, 3 seconds.
Operation 6. Flatten spring-tail with hand-hammer. Operation 6 is due to faulty castings. No time is given.
Operation 7. Drill one hole, Vi6 diameter. Burke drill press.
Operation 8. File, Ford rotary file. Page 241.
Contact Roller, Tool-Steel, T-673
Operation 1. Form on three Acme four-spindle screw machines; time for one roller, 37 seconds. Shown above.
Operation 2. Ream, Barnes drill press; time, 6 seconds.
Operation 3. Burr, Barnes drill press; time, 2 seconds. See the illustration above. Barnes drill press at right.
Operation 4. Harden. Time of operation 4, 15 minutes to harden 75 rollers. The roller and roller-pin hardening and tempering are briefly specified in the early part of this article. Furnace heat, 1400 degrees F. See page 245.
Operation 5. Temper in oil bath, constant heat, 400 degrees F.; time, 20 minutes to temper 900. Same illustration.
Operation 6. Grind on two Landis grinding machines, on arbor; time, 22 seconds, each roller. See page 246.
Roller-Pin, T-675, Tool-Steel
Operation 1. Cut off, on Acme automatic screw machine; time, 10 seconds.
There are three men in the screw-machine department of the commutator job. All the screw machines are automatic. See page 243.
Operation 2. Drill one cross-hole with No. 50 drill, Allen drill press; time, 11 seconds.
Operation 3. Burr.
Operation 4. Harden.
Operation 5. Temper in oil. See the illustration on page 245, for these three operations, 3, 4 and 5.
Clevis Pin, T-476
Operation 1. Cut off and bore one end. Acme screw machine; time, 16 seconds.
Operation 2. Countersink the other end. Allen drill press; time, 10 seconds.
Roller-Pin Locking Pin, T-676
Operation 1. Cut to length from wire coil, on automatic wirecutting machine; time, 268,000 pins cut off in 8 hours.
Commutator-Roller and Clevis-Pin Assembly, T-4474 Operation 1. Fit one T-675 pin in one T-673 roller.
Operation 2. Assemble one T-672 clevis and one T-673 roller with one T-675 pin to match up holes in T-672 and T-675.
Operation 3. Place and rivet one T-676 pin to complete assembly T-4474.
Commutator Rotor Assembly, T-4481
Operation 1. Assemble one roller, T-4474 and arm assembly with one rotor hub, T-4446, and one clevis pin, T-476, and rivet.
Operation 2. Line up roller and adjust.
Operation 3. Assemble with spring, T-469, to complete T-4481.
Operation 4. Inspect. See page 247.
These assembling and inspecting operations are made on the long metal-covered bench, marked "Assemble T-4474 and T-4481, floor plan, beginning at the south end and ending with the inspection bins at the north end. The illustration on page 247 is a view of the north end of this assembling bench, with inspection bins in fore-ground. Inspectors are taken away to give a view down the bench, looking south.
Many worn-out commutators are handled. In this picture the left-hand man, on Ford machine, is unscrewing hex-nuts, T472 , and taking out contacts. P is a Ford machine for pulling the fiber ring, T-4447, out of the case.
The vise is for general repair work. The reader, technical or nontechnical , who has looked through this Ford commutator story will find it difficult to believe that 60 men can produce 1,750 Ford commutators in one 8-hour day —16 minutes and 27 seconds of one man's time producing one complete commutator, including the case founding; and the underlying factors of this surprising efficiency should undoubtedly be displayed in detail.
How Ford Shops Make a Commutator in 16 Minutes and 27 Seconds of One Man's Time
(1) By minutely subdividing labor operations. The actual stopwatch time of each operation is given, and can be referred to by the reader in connection with the pictures that show the operation performances. Some of the operations are done in as little as 2 seconds of time. Many of the operations are the work of automatic tools.
Minute division of operations is effective in labor-cost reducing in two ways: first by making the workman extremely skillful, so that he does his part with no needless motions, and secondly by training him to perform his unvaried operation with the least possible expenditure of will-power, and hence with the least brain fatigue.
(2) The work hours are short, 4 hours at a stretch only, so that workmen in good form can, and do, stand in their tracks, working with the regular production of an automatic machine.
(3) Work-slides, successive-operation men and successive-operation tools and appliances, are so placed that one man drops a piece when his part is done, either where it is ready to the next man's hand or where the gravity work-slide will carry the piece to the next man's ready reach.
(4) Placing the case foundry on the machine floor, close to the machine tools, is a very great time-saver. Not only is the roughcase supply thus made certain, but the castings are perfectly moulded and come to the finishers in best possible form, with least possible, thought, travel, and labor, both of the head and the workmen.
(5) All operations requiring heat, melting, annealing, hardening and tempering, are performed in furnaces so located, and so grouped where more than one heating is needful, as to save all possible time expenditure.
(6) While the machine tools used are all regular commercial productions, the fixtures used with them are most elaborate, carefully designed to save movements as far as may be, and are well made, so that the workman need exercise no care or scrutiny in operating and working them.
(7) In three instances the special tools and fixtures used are unusual ; the two turret machines which produce T-671 have been so ingeniously changed as to produce more than double the work that could be turned out by ordinary handling of a turret machine, as described in detail herein. The three-spindle drilling head, also fully shown, is a marked timesaver.
The contact-seat milling and drilling fixture is very clever, and enables twelve cuts to be made in the commutator case and insulation ring with great rapidity, and perfectly to gauge, so long as the mill which makes the sinking cut in the fiber insulation remains sharp. The life of this mill is very short; the fiber is hard to cut and the mill-diameter must always be nearly the same; these mills often work only one hour for once grinding, and can be ground only a few times before they become too small in diameter. This fixture is fully shown.
(8) Constant supervision of workmen, constant work inspection, and constant watching of tool-cuts by the two tool-setters, give skilled overlooking to the work of every man on the commutator job. Many of the machine hands, though not regular machinists, are highly skilled and grind and set their own tools. Every workman is perfectly aware that he is under constant observation, and that he will be admonished if he falls below the fast pace of the department.
(9) An automatic drill chuck, the "Gronkvist," can be handled more rapidlylhan anything ever seen previously by me, and saves much time.
(10)|The workmen are suitable for the performance of their operations, and for their environment and working conditions. They are docile, and yet the physiologist will seek in vain for weak chins and narrow heads in the portraits of these workers, who are, without exception , mentally capable of concentration and determined effort, having well defined, firm chins, wide jaws, and wide heads., After reading the foregoing summary of Ford labor-cost reducing elements, the Commutator Department Head asserted its correctness, but added as follows: "I depend largely on my tool-setters for my production. The toolsetters know exactly what I want, and as long as the tool-setters have plenty of newly-sharpened tools on hand, all ready to go into the machines as soon as tools in use show loss of smooth-cutting edge, I have no trouble in keeping my production up to the 1750 per 8-hours mark.
But if there is even a very small delay in replacing a cutting tool which does not work exactly right, trouble begins." Undoubtedly this post-script is of first importance in this 16 minutes and 27 seconds achievement.
The commutator job is regarded by the Ford shop heads as being in as nearly satisfactory condition as any department of the entire plant, and the low labor-costs therein reached fully warrant the minutely detailed and profusely illustrated story here printed.