GERMANY 09Other German machine tools

Drilling machines: radial, multi-spindle and jig boring

The drilling machine, which feeds a rotating drill from top to bottom to make holes, is the most familiar machine tool. With small parts the work is moved to line up with the hole position, but that cannot be done with heavy things such as boiler plates or large castings. So the spindle head was mounted on a long arm that swings around a column, and the spindle is brought to the hole position without moving the work: so the radial drilling machine was born. The TECHNOSEUM in Mannheim explains that this type of machine was born in Britain around 1840^[9].

From overhead belts to a motor on each machine

The TECHNOSEUM holds a radial drilling machine built around 1901–1910 by Raboma (Maschinenfabrik Hermann Schoening) of Berlin. According to the museum's description, this machine was of a new design, with a motor fitted to each machine and a gearbox to change speed. However, the same model was also sold in a version driven by belt from a long overhead shaft, for factories that did not yet have electricity^[9]. In the early 20th century, factory power was in the middle of moving from steam engines and belts to electric motors, and makers catered to both.

When electric motors and high-speed steel tools came together, the power of drilling machines rose sharply. Fr. W. Hülle's 1919 textbook Die Werkzeugmaschinen (4th edition) uses the upright drilling machine of H. A. Waldrich of Siegen as an example, explaining with drawings how the motor's gearbox gives the spindle 12 speeds and how it can switch between forward and reverse for tapping. It then writes that the same company's new high-speed drilling machine carried a 100 PS motor and had a speedometer showing the cutting speed at the moment, a hole depth indicator and a feed table, and set this beside the 3–5 PS of older machines to show “how greatly the drilling machine has developed”^[11]. Because drill points could now stand heat, machines were needed to turn them faster and push them harder. The same book says that when drilling at high speed, cooling the drill with pumped cutting fluid also matters^[11].

Raboma and Kolb after the war: hydraulics and preselection

After World War II, Raboma was hit directly by the division of Germany. A 1950 report of the U.S. CIA says that the machines of the dismantled Raboma works in Berlin-Oberschöneweide had been carried off to a tractor plant in Stry, in the Soviet Union (today's Ukraine), and were in use there^[17]. Even so, Raboma carried on in Borsigwalde in West Berlin, and at the 1951 Hannover fair it showed a new radial drilling machine operated hydraulically, with many operations automated. The report also notes that Raboma had marked its 50th anniversary the year before^[19]. A French trade journal the following year introduced Raboma's type 12 Uh, listing a device for preselecting the spindle speed and feed, a device for clamping the arm and column electrically and hydraulically, and controls gathered under the spindle head, and wrote that it could drill holes up to 90 mm in diameter in steel^[20].

Also catching the eye at the same 1951 fair were the large machines of Hermann Kolb of Köln-Ehrenfeld. Kolb too was 50 years old; its machine had a column and arm of almost 6 m, a drilling radius of 5,100 mm and 4,800 mm from the floor plate to the spindle. It also showed a device that clamps the arm to the column electrically and hydraulically^[19].

Why “clamping” and “preselection”? On a radial drilling machine, every time the arm is swung to move the spindle head, the arm must be clamped firmly to the column and the spindle head to the arm; otherwise the drilling force bends the arm, and holes come out crooked or out of position. The larger the machine, the heavier and slower the clamping work. If this is done in an instant by electrics and hydraulics, and the speed and feed for the next hole are selected during machining, all the operator has to do is position the spindle and throw a lever. In drilling large work the setup time is often longer than the cutting time, and postwar improvements to the radial drilling machine aimed at cutting this “setup time”^[19][20].

Multi-spindle drilling machines: drilling many holes at once

In factories making the same part in large numbers, as in the auto industry, drilling holes one at a time cannot keep up. At the 1951 fair, Burkhardt & Weber of Reutlingen showed a special-purpose machine with 20 spindles in all, 16 for drilling and 4 for tapping, and a 1,250 mm rotary table indexing to six stations. It handled the angled holes for the fuel injection nozzles in the cylinder head of a passenger-car diesel engine (inclined 15°, each pair offset by 3°), from pilot drilling and finishing to reaming and tapping, and each time the table indexed, two cylinder heads were finished. The spindle head feed, the rotary table and the clamping were all hydraulic^[19].

Jig borers: Lindner and coordinate accuracy

The machine that perfected hole “position” is the jig borer, which bores holes for jigs and gauges accurately by coordinates. Herbert Lindner of Berlin started his company in 1918, began with accessories such as dividing heads for milling machines, and put a thread grinding machine on sale in 1926. In 1933 he showed his first jig borer (Lehrenbohrwerk) at the Leipzig fair, and in 1936–37 filed patents for coordinate boring machines. The biographical dictionary Neue Deutsche Biographie writes that about 1,200 of these jig borers had been built by 1968^[10]. SIP of Switzerland is the best-known name in jig borers, but Germany too had a specialist maker that came in from the precision technology of thread grinding.

On to NC coordinate drilling machines

In the 1960s the old-established radial drill makers moved to NC as well. A British technical journal of 1960 described Kolb's coordinate boring machine as having “program control,” which stopped the table by means of a magnetic tape and a reading head for each axis^[24]. In the index to the late-1969 volume of the British trade journal Machinery and Production Engineering, articles on Kolb's coordinate drilling machine KBN E 30 (with Fanuc open-loop NC) and Raboma's NC coordinate drilling machine Rabomat appear side by side^[26]. With the drawing's coordinates given on tape and the table moving automatically to the hole position, neither marking out nor jigs are needed. That a Japanese Fanuc NC control was used here is taken up later under “Links with Japan.”

Horizontal boring machines, cylinder boring machines, vertical lathes

The horizontal boring machine finishes holes in large workpieces to accurate size and position with a boring bar mounted on a horizontal spindle. Lining up several bearing bores in a straight line at the right spacing, in machine tools, generator and pump casings or gearboxes, is work that lathes and drilling machines cannot do. The horizontal boring and milling machine (Bohr- und Fräswerk in German) extends the spindle back and forth, moves the spindle head up and down the column and moves the work on the table, handling drilling, boring, facing and milling on one machine.

Union: founded in 1852, a specialist in horizontal boring machines

When German horizontal boring machines come up, the first name mentioned is Union of Chemnitz. The official German catalog for the 1910 Brussels World's Fair introduces Werkzeugmaschinenfabrik „Union“ (vormals Diehl) as “the second-oldest machine tool factory in Germany,” and writes that D. G. Diehl founded it in 1852 and that it became a stock company in 1872^[2]. In an exporters' directory of the 1870s, too, „Union“ advertised itself as “founded 1852,” offering lathes, drilling machines, lathes for turning locomotive and wagon wheels, and even woodworking machines^[3]. In its early years Union was a machine works that made everything.

The turning point came in 1900. According to the official catalog, from that year Union switched to being a factory making only horizontal boring machines (Horizontalbohrwerk), always building around 150 machines of its own design (some patented) and supplying leading companies in France, Belgium, Britain, Austria, Italy and Russia. In February 1910 it also built a large showroom where finished machines were run for visitors^[2]. Hülle's 1919 textbook also presented Union's horizontal boring and milling machine in detail, with six figures^[11].

What it meant to “specialize in one type.” In the 19th century a machine works normally made lathes, planers and drilling machines alike. Union specialized in horizontal boring machines so that it could make parts of the same form in batches and build up its design and assembly experience on one machine type. Large machines change size with each customer's order, but if the spindle head and feed mechanisms are kept common, high accuracy can be achieved with short delivery times. As in the American machine tool industry, the era of “specialist makers” began in Germany around this time (see Chapter 2).

After the East–West division Union belonged to East Germany, and went on making horizontal boring machines as the people-owned enterprise VEB Werkzeugmaschinenfabrik Union Karl-Marx-Stadt. The Industriemuseum Chemnitz preserves trade-fair models of a horizontal boring and milling machine with facing head offered to customers in the late 1980s, the BFT 90/3at (1985), and a horizontal machining center with pallet change and automatic change of 80 tools, the CBFK 90/1 (1988). When the real large machines could not be brought to a trade fair, models like these were used^[28][30]. A horizontal boring machine company adding automatic tool change and moving on to MCs followed the same course as in the West.

Schiess: large machines from Düsseldorf

In the Rhineland in the West, the leading name in large machine tools was Ernst Schiess. Born in Magdeburg, Schiess studied at the technical schools of Hannover, Karlsruhe and Zürich and in British factories, and in 1866 opened for business in a rented workshop with six workers in Oberbilk near Düsseldorf. Starting with repairs and steam engines, he had a machine works by 1869 and a foundry by 1872, and in time metal-cutting machine tools became the main business. 440 people worked there in 1891 and about 1,000 around 1900, and by then the company is said to have sold about 7,000 machine tools around the world^[6]. In 1898 Schiess was at the center of founding the association of machine tool makers (today's VDW), and served as its chairman until his death^[6].

In 1906 the company became Ernst Schieß AG, and in 1925 it merged with Defrieswerke of Düsseldorf to become Schieß-Defries AG. After World War II the works was entirely dismantled, but production resumed in 1951 as Schieß AG^[6]. At the Hannover fair the same year, 1951, it showed the horizontal boring and milling machine WBF 16, with a 160 mm spindle^[19].

Scharmann, Dörries, Droop+Rein

There were other major makers of horizontal boring machines, too: Scharmann, founded in 1885 in Rheydt (today's Mönchengladbach), and Droop+Rein, founded in 1890 in Bielefeld^[7]. At the 1951 fair, Scharmann showed table-type and floor-type machines (the work sits on a floor plate and the column moves) with 120 mm spindles, and Droop & Rein a machine with a 150 mm spindle^[19]. In 1884, in Vussem in the Eifel region, Dörries got its start. Dörries and Scharmann came together under the Voith group in 1988, and in 1993 Dörries Scharmann took over the troubled Schieß AG^[7][6]. In 2011 the group was bought by StarragHeckert of Switzerland^[7].

Cylinder boring machines, and machines “brought to the work”

To bore the long cylinders of steam and gas engines, special cylinder boring machines were used. Hülle's textbook presents the machine of Otto Froriep of Rheydt (four feed rates for the boring head, with rapid traverse in both directions) and that of Collet & Engelhard of Offenbach (founded 1862, strong in machinery for railway workshops)^[5]. The Collet & Engelhard machine turned the boring bar from a motor through a belt, gears and a large worm, and fed the bar itself; the feed screw was placed outside the bar so as not to weaken it^[11]. The same company also built portable machines that drill and plane by placing a large workpiece on a floor plate and bringing the machine to it. Hülle writes that work on steam turbine casings, with many holes and seating faces, fostered such machines^[11].

Vertical lathes: turning heavy disks laid flat

For turning large-diameter disks and rings, the vertical lathe (Karusselldrehmaschine), which turns the work laid on a horizontal faceplate, is the right machine: the work does not sag under its own weight, and it is easy to center just by setting it down. At the 1951 fair Schiess showed a fast single-column vertical lathe with a 1,000 mm faceplate, about 30 kW and 16 speeds up to 310 rpm, the EK 100, and a two-column vertical lathe with a maximum turning diameter of 4,000 mm and a cutting force of 8 t. On the large machine, the speed is selected electrically from a remote control panel, and the gears are shifted hydraulically^[19]. The history of the lathe is covered in Chapter 5, “The Lineage of German Lathes”.

Planers, shapers, slotters and gantry machines

The planer moves a long table carrying the work back and forth and cuts flat surfaces with a fixed tool. It was indispensable for making long, flat, accurate surfaces such as the guideways of machine tool beds. The shaper moves the ram (the arm carrying the tool) back and forth to cut small work, and the slotter moves the ram up and down to cut keyways and internal shapes. All of them “cut with one tool on a reciprocating stroke,” so the return stroke is wasted time. The history of these machines is also a history of efforts to speed up the return and make reversing reliable.

Billeter & Klunz: the open-side planer and better reversing

Hülle's 1919 textbook writes that in the open-side (Einständer) planer, which supports the crossrail on a single column, the leader was Billeter & Klunz of Aschersleben. With a column on only one side, work wider than the table can be planed by placing an auxiliary support on the other side. The company also built heavy-cutting machines with four tool heads and special types for machining large flywheels^[11]. Founded in 1857, the company was by 1910 a firm of about 300 people making only planers and pneumatic hammers, and in 1930 it concluded an agreement with Giddings & Lewis of the US dividing up production and sales territories^[2][4].

According to the same book, planers with high-speed steel tools ran at 12–20 m/min for roughing, 8–12 m/min for finishing and 18–30 m/min or more on the return^[11]. Stopping the heavy table and running it back every stroke needs a strong clutch. Billeter & Klunz early on used a mechanism that reverses direction by switching belt pulleys with electromagnets, which Hülle calls “a welcome advance at the time,” while noting that heavy wear led to other types of clutch becoming widespread^[11]. The company also held a patent (DRP 146 076) for moving the tool and table in opposite directions at the same time, adding their speeds in cutting and return^[11].

Shapers and slotters

As an example of a shaper, Hülle cites the machine of Wotanwerke of Leipzig. It was for small work with strokes of up to 600–800 mm; the table moved up and down and side to side, and could also be swiveled up to 90°. In types driving the ram by rack and pinion, clutches were switched at each end of the ram's stroke to speed up the return^[11]. As an example of a heavy slotter he cites the machine of Schiess of Düsseldorf, explaining how the longitudinal, cross and rotary feeds of the table are taken from the same shaft^[11]. At the 1951 fair, Maschinenfabrik Ravensburg ran the SL 500, a large slotter with a 1,000 mm stroke, with the Leonard system combining a generator and motor. The cutting and return speeds could be varied steplessly between 4 and 27 m/min, and the report praised it as being as easy to use as hydraulics while easier for factory staff to repair when it broke down^[19].

The shaper has now all but disappeared from factories. At the 3-Städte-Depot in Hückeswagen there is a shaper built around 1950 by Klopp of Solingen, repaired even after the 2021 floods and run for visitors^[18].

Waldrich Coburg: from planers to gantry machines

How did a planer company become today's maker of large gantry machines? A good example is Waldrich Coburg. In February 1920 Adolf Waldrich and Emil Hardt started Globuswerke in Coburg, beginning with machine tool repair. In 1926 it moved to its present site and became Maschinenfabrik Adolf Waldrich, and in 1936 it showed hydraulic drives at the Leipzig fair. When his son Otto Waldrich took over in 1950, it began volume production of planers, also built machines combining grinding and milling, and from 1955 guideway grinding machines and surface grinders became its main products^[13]. The report on the 1951 fair also cites, as examples of planers, Waldrich's heavy planer and a two-column standard planer in the VDF display (Boehringer and Billeter)^[19].

Waldrich Coburg, which delivered its first NC machine in 1971, delivered in 1973 the first of its gantry-type milling machines whose columns travel with the gantry to Kraftwerk Union (Mülheim), maker of power plant equipment. In 1975 it built a gantry milling machine with a 5,000 mm table width and 18,000 mm clamping length^[13].

From planing to “gantry milling.” Because a planer cuts with a single tool on a reciprocating stroke, return time and edge wear were always a problem. Milling with a rotating carbide face mill cuts the same flat surface with no return and many times faster. Mounting rotating milling spindle heads on the planer's heavy gantry frame (two columns and a crossrail) gave the gantry milling machine (planomiller), and adding NC and even grinding heads for finishing guideways gives today's large gantry machine. Waldrich Coburg's path from planers to guideway grinders, NC and gantry milling machines is exactly this course^[13]. Gantry MCs are also covered in Chapter 6, “The Lineage of Milling Machines and MCs”.

Later, Otto Waldrich sold the company to the American Ingersoll group in 1986; after Ingersoll's bankruptcy it was taken over at auction by the Herkules group in 2004, and in 2005 by China's Beijing No.1 (Beijing No.1 Machine Tool Plant)^[13].

Broaching machines

A broaching machine finishes keyways, splines, square holes and the like by passing a long tool lined with many teeth that grow slightly larger one after another (the broach) through or over the work just once. Because teeth from roughing to finishing are lined up on one tool, the shape is settled in a single stroke, making it indispensable in automotive and machinery plants that make large numbers of identical parts. On the other hand, the tool is made specially for each shape, and a large pulling force is needed.

The report on the 1951 Hannover fair presents the broaching machine exhibits together. Kurt Hoffmann of Pforzheim showed a vertical internal broaching machine whose broach slide was moved hydraulically. It used broaches up to 1,750 mm long with a pulling force of 12 t and a stroke of 1,200 mm, and on the return the tool automatically backed away from the work. Also on show were a two-column machine with a pulling force of 3 t, a 10 t machine with a rotating work table, horizontal machines of 5 t and 10 t, and vertical and horizontal broaching machines by Forst; small external and internal machines with a pulling force of 2 t and an 800 mm stroke also appeared for the first time. The report notes that some were of welded construction^[19].

Why hydraulics? In broaching, many teeth bite into the work at the same time, so a large force must be kept up at a constant speed throughout the stroke. Mechanical machines pulling with a screw or rack can do it, but hydraulics allow force and speed to be adjusted steplessly, and stopping on overload is easy. Rotating work tables and tools that back away on the return were devices for keeping the machine working even while parts were loaded and unloaded^[19].

Special-purpose machines, machining lines and FMS

If you are making hundreds of thousands of the same part, it is faster and cheaper to line up special-purpose machines for each operation and move the work automatically than to line up general-purpose machines and carry parts by hand. This is the idea of the transfer machine (transfer line). At the 1951 fair, Burkhardt & Weber of Reutlingen showed part of a machining line linking three single-direction special-purpose machines with automatic transfer of the work. It was a line machining the four faces and the angled spark plug holes of a car cylinder head; the work slid on hardened rails, which were lifted hydraulically to advance it 900 mm at a time. The transfer speed was adjustable, and the report notes that such equipment requires special attention to chip disposal^[19]. The company's practice of building machines by combining tool slides and spindle heads as “standard units” was also presented as one of its strengths^[19].

A dedicated line is good at making one part in large numbers, but must be rebuilt when the part changes. So the FMS (flexible manufacturing system) brought NC machines and automatic handling together under computer control so that various parts could be run. According to the company history of Starrag of Switzerland, East Germany's Heckert (VEB Werkzeugmaschinenkombinat „Fritz Heckert“) put into operation the first FMS, PRISMA 2, in Chemnitz in 1971^[7]. Heckert became Heckert Chemnitzer Werkzeugmaschinen GmbH under the Treuhand (the trust agency) in 1990 and was taken over by Starrag in 1998^[7]. The East German machine tool Kombinats are described in detail in Chapter 3, “War and the East–West Division”.

Electrical discharge machines (EDM)

Electrical discharge machining fires tiny sparks (discharges) tens of thousands of times between a tool electrode and the work, in oil or water, melting away the work little by little. Because there is no cutting tool, even hard materials such as hardened steel and cemented carbide can be given fine slots and complex die shapes. According to the National Museum of Nature and Science's “Survey of the Systematization of EDM Technology,” the Soviet couple Lazarenko proposed this process in a paper in 1943 and filed a patent, and research spread from Soviet-influenced Eastern Europe to Western Europe, including Britain, Switzerland and Germany^[15].

AEG-Elotherm: power supplies and electrochemical machining

One West German company that took up EDM was AEG-Elotherm of Remscheid. As checked in DEPATISnet (the German Patent and Trade Mark Office's search), the company also patented in Britain an EDM power supply circuit it had filed in Germany in January 1965 (GB 1 096 119, published 1967)^[25]. The speed and surface finish of EDM depend heavily on the power supply, which sets the energy and interval of each spark, so makers competed on power supply circuits. AEG-Elotherm also filed patents on equipment for electrochemical machining (ECM), which dissolves metal away by electrolysis (GB 1 280 496, filed 1969)^[27]. Both are ways of “cutting with electricity,” used for shapes cutting tools cannot reach and for hard materials.

Agie and Charmilles of Switzerland, and Japan catching up

In the German-speaking world, the world leaders in EDM were Agie and Charmilles of Switzerland. According to the same survey, in 1969 Agie completed the NC wire EDM machine DEM-15 and showed it at an exhibition in Paris; the world's leading makers at the time were Agie and Charmilles in Europe and Elox in the U.S.^[15]. From the late 1970s Japanese makers caught up in performance and gained the edge on price, and it is said that European makers sometimes took them on in patent disputes^[15].

The German electrical maker Siemens also has a place in EDM history. On automatic wire threaders, which rethread the wire by themselves when it breaks, the same survey writes that the first unit in Japan was completed by FANUC with technology brought in from Siemens, and that reportedly no one but Siemens had put it into practical use at the time^[15]. For unattended overnight running, it was essential that the machine not stop when the wire broke.

Since then, most European and American EDM makers have left the market. The survey sums up that today's world market is shared by GF Machining Solutions of Switzerland (formerly Agie and formerly Charmilles), ONA of Spain, EXERON of Germany, and five Japanese companies^[15]. Inspection of today's EDM machines and management of the machining fluid are covered in the EDM maintenance .

Presses, sheet metal machines and laser machines

Compared with machine tools that shape by cutting, presses and sheet metal machines shape by punching, bending and drawing sheet. Car bodies, appliance housings and machine covers are almost all made from sheet metal. Germany has two world-leading companies: Schuler in presses and Trumpf in sheet metal machines and lasers. This chapter touches only lightly on forming machines and focuses on Trumpf's lasers.

Schuler: from hand-cranked to powered and hydraulic presses

Schuler of Göppingen started from a locksmith's workshop founded in 1839 by Louis Schuler (the father), and from 1852 also made sheet metal machines. His son Louis Schuler, who had worked at Zimmermann's machine tool works in Chemnitz and studied at the Chemnitz technical school, returned in 1863 and turned the workshop into a machine works, and in 1875 showed power-driven eccentric presses, drawing presses and shears at a sheet metal exhibition in Nürnberg. In 1895 it obtained a patent (DE 84410) for a hydraulic drawing press driven by two hydraulic cylinders; pushing the slide hydraulically rather than mechanically applied the force evenly and improved the finish of deep drawing. From the 1920s it supplied body presses to major car makers in Europe and the U.S.^[1]. Inspection of today's press machines is covered in the press maintenance .

Trumpf: from flexible shafts to nibbling machines

Trumpf began in 1923, when Christian Trumpf bought the Julius Geiger works in Stuttgart and made flexible shafts (tools driven through a bendable shaft). In 1934 it brought out its first electric hand shear for cutting sheet metal, the HSP 201, and in 1937 changed its name to TRUMPF & Co. In 1939 it made aircraft parts as a subcontractor, and the company's own materials state that a third of its workers were forced laborers brought from France^[14]. In 1947, after the war, it built the TAS stationary curve shear (a machine that cuts sheet along curves), and Trumpf became a sheet metal machine company^[14].

Enter Berthold Leibinger, who joined as an apprentice in 1950. Leibinger, whose graduation project was on improving curve-shear cutting, was involved in 1957 in patent applications for a system guiding the sheet by coordinates (which the company calls “the starting point of NC”) and for a nibbling device^[14][21][22]. Nibbling punches sheet with a small round punch, shifting it a little each time, to cut holes and outlines of any shape without making a die. With a pilot (guide pin) inside a hollow punch and coordinate guidance, the first stationary copy and coordinate nibbling machine was born in 1958^[22][23]. That year Leibinger went to work at Cincinnati Milling Machine Co. in the U.S., returning in 1961 as head of design^[16][14] (Cincinnati is a company that appears in the American milling machine chapter).

Sheet metal and NC were a good match. In nibbling and punching, the sheet only has to be moved in X and Y and struck at set positions, so far simpler control is needed than for cutting machines. Connect numerical commands to a coordinate table drive, and you have an NC machine. In 1967 Trumpf's TRUMATIC 20, the first sheet metal machine with numerical continuous-path control, came onto the market^[14][22]. In Japan too, the first NC control in private industry, developed in 1956 by Fuji Tsushinki (later FANUC), had a turret punch press as its first target^[37][38].

Punch–laser combination machines, and lasers of its own

In 1978 Leibinger, now president, brought a CO2 laser back from a visit to the U.S. The following year, 1979, Trumpf brought out the TRUMATIC 180 LASERPRESS punch–laser combination machine and entered the world of lasers. The beam sources were American-made CO2 lasers of 500 W and 700 W^[14][22]. Fixed shapes such as round and square holes are punched quickly, and curved outlines that are hard to punch are cut by laser. Doing both on one machine made it a machine that could make small batches of parts without dies. In 1981 the 1,000th TRUMATIC was sold^[22].

Leibinger insisted on making the laser source in-house. In 1985 Trumpf showed its first CO2 laser developed and built in-house, the TLF 1000 (1 kW), and became a laser source maker too^[14][22]. In 1987 it brought out the TRUMATIC L 3000, a flat-bed laser machine with “flying optics” in which the mirrors (optics) move instead of the heavy sheet, and at EMO (Hannover) in 1989 the TRUMATIC 240 LASERPRESS, carrying a “folded” laser whose beam path is folded to make it compact^[14]. In 2003 it showed a prototype 4 kW disk laser, and in 2015 it also set up an additive manufacturing division^[14]. The spread of Trumpf's lasers and the NC era is also touched on in Chapter 4.

Coordinate measuring machines

Checking that machined parts match the drawing is also inseparable from the history of machine tools. A coordinate measuring machine (CMM) moves a touch probe in the three directions X, Y and Z, collects the coordinates of points on a part's surface and calculates hole positions and face angles. Unlike measuring one spot at a time with calipers or micrometers, it can measure many dimensions of a complex part by a fixed procedure, the same way any number of times.

The representative of German metrology is the optical company Carl Zeiss. Founded in Jena in 1846 (head office now in Oberkochen), Zeiss first showed measuring instruments at the Leipzig Spring Fair in 1919, and marked 2019 as “100 years of industrial metrology”^[12]. Underlying this is the comparator principle (Abbe's principle), shown by Ernst Abbe in 1890 with a thickness gauge: aligning the object being measured and the scale on one straight line keeps errors small. In 1926 Zeiss brought out the first universal measuring microscope, which could measure all five elements of a thread without reclamping^[8][12].

In 1973 Zeiss brought out the UMM 500. A CNC coordinate measuring machine combining a touch probe, an HP 9810 desktop calculator and Zeiss's own measuring software, it could measure to 0.5 µm without the work first having to be precisely realigned. Zeiss calls it “the first CNC coordinate measuring machine.” Following its success, the precision measurement division became Industrielle Messtechnik (industrial metrology) in 1977, and in 1978 brought out the WMM 550/850 series for use on the shop floor^[8][12].

The measuring machine corrects the machining. A measuring machine with a computer can not only measure but also calculate corrections to the machining settings from the results. A 1987 NASA report says that the American helicopter maker Sikorsky developed a method of measuring about 45 points on the tooth flanks of aircraft spiral bevel gears on a Zeiss UMM 500, and from the differences from a master gear calculating corrections to the gear grinding machine settings with Gleason software^[29]. It was a shift from adjusting tooth contact by craftsmen's feel to deciding it by numbers. Gear measurement and grinding are covered in Chapter 8, “The Lineage of Gear Machines”, and how to use today's measuring tools in the inspection and measuring tools database.

Additive manufacturing (metal 3D printers)

Additive manufacturing builds shapes by stacking thin layers one at a time. Whereas cutting “removes what is not needed from a block,” additive manufacturing “puts material only where it is needed,” so it can make shapes that cannot be cut, such as dies with internal cooling channels or lattice structures for lightness. In metal additive manufacturing, the main method is to sinter or melt thinly spread metal powder with a laser, and in this technology Germany is one of the world's centers.

EOS: from stereolithography for BMW to powder sintering

In April 1989 Hans J. Langer founded EOS in Gräfelfing near Munich. The aim was to make objects directly from CAD data with a laser. In 1990 BMW became the first customer, ordering the STEREOS 400 stereolithography machine, which cures resin with light^[31][32]. In 1994 EOS brought out the P 350, its first powder sintering machine (sintering plastic powder with a laser), developed for BMW. EOS calls it Europe's first plastic powder sintering machine^[32][31]. With Electrolux, which had bought Europe's first stereolithography machine, it jointly built a machine for DMLS, sintering metal powder directly with a laser; this later became EOS's largest market^[32]. By 1997 EOS had acquired the rights to powder sintering patents worldwide and had become a powder sintering specialist^[31].

Fraunhofer ILT's basic patent: “fully melting” the powder

To make metal parts strong enough to use as they are, the powder must not just be sintered but fully melted into metal with no voids. In December 1996 Wilhelm Meiners, Konrad Wissenbach and Andres Gasser of Fraunhofer ILT (Institute for Laser Technology) in Aachen filed for a method of spreading metal powder layer by layer and melting set areas with a laser to make parts exactly to CAD data (DE 196 49 865, published 1998)^[33]. This is the basic patent for today's mainstream metal 3D printing, “laser powder bed fusion (LPBF, also called SLM)”. According to ILT's 2021 announcement, when the work began it was given only half of one researcher's time, and the first targets were materials with clear uses, such as cobalt-chromium alloys for dental implants. The world market for metal additive manufacturing in 2019 was about €2 billion, more than 80% of it LPBF^[34].

Concept Laser and GE, and Trumpf's entry

In 2000 Frank Herzog and others founded Concept Laser in Lichtenfels, and in 2001 put their first metal additive manufacturing machine on sale. The process is called LaserCUSING. In October 2016 GE of the U.S. agreed to buy 75% of the company's shares for $599 million^[35]. Trumpf, the sheet metal and laser company, also set up an additive manufacturing division in 2015^[14], and Meiners, one of the inventors of ILT's basic patent, was working at Trumpf as of 2021^[34]. Installations of EOS industrial 3D printers reached 5,000 in 2025^[31].

What changed in machining on the shop floor. Additive manufactured parts have rough surfaces as built, and their dimensions are not as accurate as machined parts. Mounting faces and holes are still finished on machining centers and lathes. That is why machines combining additive manufacturing and cutting in one unit were also born (for a Japanese example, see “Links with Japan” below). Additive manufacturing did not replace cutting machines; it created a new division of labor: build the shapes that can't be cut, then finish them by cutting.

Links with Japan

Japanese NC on German coordinate drilling machines

In the index of a British trade journal of 1969, the coordinate drilling machine KBN E 30 by Kolb of Köln is listed as “with Fanuc open-loop NC”^[26]. Open loop means an NC that turns the motor by the number of commands without measuring the table's position and feeding it back. So an old-established German radial drill maker was offering a coordinate drilling machine with a Japanese NC control at the end of the 1960s. The history of Japanese radial drilling machines and jig borers is in The Lineage of Drilling and Boring Machines. Japan's first jig borer was modeled on a machine by SIP of Switzerland, but in Germany Lindner built jig borers on its own (see the section above).

Wire EDM: from Siemens to FANUC, and Japan takes the lead

In EDM the ties between Japan and the German-speaking world run even deeper. The National Museum of Nature and Science survey writes that FANUC completed Japan's first automatic wire threader with technology brought in from Germany's Siemens^[15] (The Lineage of EDM Machines, 1979). Meanwhile, from the late 1970s Japanese makers caught up with Switzerland's Agie and Charmilles, and at times European makers took them on in patent disputes^[15]. Around 1990, Japanese patents on EDM power supplies were also registered in Germany, Switzerland, the U.S. and Italy, and the survey concludes that “the era of suffering under prior Western patents gave way to an era in which Japan leads development”^[15].

Trumpf's Yokohama subsidiary, and NC for sheet metal

In 1978, the same year Leibinger brought a CO2 laser back from the U.S., Trumpf set up a subsidiary in Yokohama^[14]. It was its overseas base after Switzerland (1963) and the U.S. (1969), and its first subsidiary in Asia^[14][22]. Sheet metal machines were NC's first stage in Japan too: the first NC control in private industry, developed in 1956 by Fuji Tsushinki (later FANUC), had a turret punch press as its first target^[37][38] (The Lineage of Japanese Lathes, 1956).

Combined metal additive and cutting machines

Japanese makers developed the metal powder bed fusion that began with Fraunhofer ILT's 1996 patent in the direction of combining it with cutting. In 2002 Matsuura Machinery developed a machine combining metal laser sintering, which solidifies metal powder with a laser, with machining-center cutting in one unit^[39] (The Lineage of Multitasking and 5-Axis Machines). Japan tried to achieve within a single machine the division of labor of “building the shapes that can't be cut by additive methods, then finishing them by cutting.”

FAQ

Which are the leading German makers of radial drilling machines?

The ones confirmed in this chapter are Raboma (Hermann Schoening) of Berlin and Hermann Kolb of Köln-Ehrenfeld. Both marked 50 years in business in 1950–51, and at the 1951 Hannover fair they exhibited hydraulically operated radial drilling machines and large machines with a 5,100 mm drilling radius. By the late 1960s both had moved on to NC coordinate drilling machines (Kolb KBN E 30, Raboma Rabomat). The TECHNOSEUM in Mannheim holds a Raboma machine from about 1901–1910.

What kind of company was Union, the long-established maker of horizontal boring machines?

It was a machine tool works started by D. G. Diehl in Chemnitz in 1852; the official catalog of the 1910 Brussels World's Fair introduced it as "the second-oldest machine tool works in Germany." From 1900 it specialized in horizontal boring machines, always having about 150 in production and supplying them across Europe. After the division of Germany it became East Germany's VEB Werkzeugmaschinenfabrik Union Karl-Marx-Stadt, and in the 1980s it built the BFT 90/3at horizontal boring and milling machine and the CBFK 90/1 machining center.

Why did Trumpf become a maker of laser cutting machines?

It started out making hand shears and curve shears for cutting sheet metal, and nibbling machines that punch out little by little with a small punch. In 1957 it patented guiding sheet by coordinates, and in 1967 it brought out the TRUMATIC 20 NC sheet metal machine. To cut curved contours that were hard to do with a punch, in 1979 it brought out the TRUMATIC 180 LASERPRESS, a combined punch and laser machine with an American-made CO2 laser, and in 1985 it built its own CO2 laser, the TLF 1000, becoming a maker of laser sources as well.

Was the metal 3D printer (laser powder bed fusion) born in Germany?

The basic patent for today's mainstream method, "completely melting metal powder layer by layer with a laser," was filed by Fraunhofer ILT in Aachen in December 1996 (DE 196 49 865). In powder sintering, EOS (founded 1989) brought out plastic and metal machines in the 1990s, and Concept Laser started in 2000. However, EOS's first machine was a plastic stereolithography machine, and building shapes by stacking layers existed before that, so it was not "born in Germany alone."