Sumitomo electric industries - PM parts manufacturing for the 1990s

Sumitomo Electric Industries · PM Parts Manufacturing for the 1990s The ever increasing and burgeoning growth of Japan's manufacturing economy in recent years has provided a stimulating environment in which companies, including those invoh'ed in PM parts manufacturing. can accelerate the re·equipment and modernization of existing facilities, and introduce factory automation and computer integrated manufacturing (ClM). Sumitomo Electric Industries Ltd (SEI) is a prime example of such an operation with one of the largest and possibly the most advanced PM plant in the world at its subsidiary - Okayama Sumiden Seimitsll Ltd in Nariwa. a short distance from Okayama City. MPR recently had the privilege to revisit the plant after an absence of 10 years to find the human population in the plant augmented by a host of'musical' and non·musical robots. and a number of new and lotally automaled CIM lines. These will be described later in this report. SEI as an independent manufacturing group within the huge Sumitomo conglomerate saw net sales rise by 10% to Yen 605 billion in fiscal year ended March 1989, with profits also up at Yen 13.5 billion. The company spent a staggering Yen 22 billion (3.6% of sales) on research and development in its last fiscal year. Tetsuro Kawakami, SEI's president stated in the company's annual report that 'in the present healthy economic environment, SEI was able 10 strengthen its production bases at home and abroad, and also develop new products and technology as the company continues to diversity its product range'. The current range of SEI products is still based on electric wires and cables (51.8% of sales). with special steel wires (6%), sintered alloy

products (10.8%), brake products (5.9%), hybrid products (5.1 %1. and 'other products' making up the balance.

SINTERED ALLOY PRODUCTS SEl's interest in PM goes back to as far as the 1920s when it started to produce tungsten carbide drawing dies for electric wire and cable. This was subsequently expanded to include WC cutting tools, tungsten heavy metals. PM bearings and later the production of structural PM parts, the latter being the subject of this report. Whilst the 'nerve centre' of the Sintered Alloy group remains in !Iami. where both PM parts and hardmetals arc produced, and where is situated the company's modern research centre, PM production is also carried out at eight additional plants located throughout Japan. Of these five arc devoted to hardmetals, two for PM parts/bearings, and one plant is devoted exclusively to the finish machining of PM parts. Sales ofall types ofsintered products made by SEI in Japan rose by 17.5% in 1989 to Yen 65.2 billion. In addition to its Japanese operations, the company operales a number of PM plants abroad with the most recent additions including Korean Sintered Metals Ltd· a joint venture with Korea Tungsten Mining Co. ~ for sintered alloy products, and Engineered Sintered Components Inc. - a joint venture with the Eaton Corp. in the USA to establish a plant primarily for the automotive PM parts. The latter plant is based in Troutman, North Carolina. and includes fo'ur compacting

FIG. 1 Sintered sensor rings used in ABS braking systems

MPR June 1990

presses lip 10 500 tons and two sintering furnaces. SEI is also sun'eying a number of options for a possible European PM plant, but has as yet not decided which option this would be.

PM PARTS SEI's range ofstructural PM parts is dominated by those manufactured for the automotive industry which today accounts for 72% of sales compared with 63% only five years ago. This is followed by compressor parts (15%). industrial parts (8%), and electronics which has dropped from 9% in 1985 to 5% in 1989 mainly due to the declining demand for stepping molar parts. This said Nobuo Furukawa. director. manager of the Powder Metal Products Division, is allributed to the replacement of floppy disk drives in personal computers by hard disks. He said thaI total sales for structural PM parts was running at an average of Yen 1.477 million per month in the first six months of 1989. 43% (57%) of sales comprised small to medium sized PM parts. 23% (14%) large size PM parts, 11 % (6%) high strength PM parts. 9% (5%) pump rotors. and tho balance of 14% (24 %) for other types of PM parts. The figures in brackets arc the percentages of the same product groups five years ago. In terms of tonnage production Mr Furukawa reported that output had increased from under 900 tonnes per month in 1985 to around 1400 tonnes per month in 1989. ariseof55%. Ofthis around 300 tonnes/month is produced at the Hami PM parts plant and balance at Okayama Sumiden Seimitsu making SEI the largl!st PM part producer in Japan. Mr Furukawa told MPR that whilst the growth in the established range of small to medium size and medium strength PM parts has not been very significant in recent years, the company is confident that thel'e are still considerable growth opportunities for PM in new materials. particularly those having having good wear resistance or high strength, or a combination of both. For example, SEI has developed two new PM alloys designated FMC-l1 (Fe-Cr-W-Mo-V-C) and FMC-31 (Fe-Cr'\V-Mo-V-C) having HRA hardness of 55-75 and 60-75 respectively which amused to

FIG. 2 Selection o[parachoida/ rotors produced by Sumito11lo Electric's Sintered Alloy DIvision 417

FIG. 3 Helical gears and cam

FIG. 4 Multi-level clutch hub

FIG. 5 Complex P,':f part assemblies produced by sinter bonding

FIG. 6 Selection ofhigh strength PM steel parts

Fe-Mo- Mn-Cr-C). The tensile produce the vanes for rotary strength of these materials rises compressors at a rate of 400,000 from around 800 N/mm 2 in the pieces/month. as-sintered condition to 1400 SEI is a market leader in the when heat treated. N/mm 2 production of sensor rings used in Fe-Ni-Mo-Cu-C alloy powder is also anti-lock braking (ABS) systems used to produco powder forged (Fig. 1) with an 80% share of the PM inner and outer races of one-way parts for this sector said Mr clutches, parking gear for automatic Furukawa. There arc currently five transmission, turbine hub, truck different ABS sensor rings in and synchronizer rings production at a combined rate of synchronizer hubs. 200,000 pieces/month. Some of A process which SEI believes will these are Dacrotized (zinc metallic challenge powder forging in the coating) to improve corrosion future for the production of heavy resistance, and some are nickel duty gears made from 4600 low plated and then chromium plated. alloy steel powders and races used Inner and outer rotors for oil FIG. 7 1500 ton hot extrusion press used by Sumitomo Electric to in cars, is pressing and high pumps (Fig.2) are big business at produce complex shapes from aluminium aIloy pOII'ders temperature sintering followed by SEI with output of 500,000 pieces per month. Parachoidal rotors developed by production, plus multi-level clutch hubs cold repressing (sizing) and deep case (FigA), composite PM parts produced by hardening. Using this process a rolling contact the company arc produced to close dimensional tolerances in order to reduce the sinter-bonding (Fig.5), and high strength PM fatigue strength of 1665 MPa can be achieved noise levels in pumps. and SEI expects further parts based on the company's CODE H which is far superior to through hardened materials (Fig.6) which include rotors and cam PF4600 and wrought carbon steel. growth in this sector as power steering and automatic transmissions become more rings for power steering, starting pinion gears, sm has for a number of years been shifting levers, clutch sprockets, cam gears for investigating the production of PM parts from prevalent. aluminium alloy powders, but found it PM helical gears with helix angles up to 30 farm equipment, etc. Most of the high strength PM parts are difficult to obtain the desired mechanical degrees, and non- spherical cam gears (used in rice planting machines) shown in Fig.3 are properties and cost per part using produced from partially prealloyed powders (Fe-Cu-Mo-C, Fe-Ni-C, Fe-Ni-Cu-Mo·C and conventional powder consolidation and further examples of PM parts currently in 418

MPR June 1990

FIG. 8 HiZh strength P.\{ aluminium mnes. rotors. Oil pump gears and orbital scroll

FIG. 9 \'ien' of the Okayama Sumiden Seimitsu Ltd plant at Narilm

FIG. 10 Computersied blending facility at ass sintering techniques. Mr Yoshinobu Takeda from the SEI Research Laboratories in Itami told MPR that these problems were overcome by the usc of hot extrusion to ncar net shape of cold isostatically pressed aluminium powder compacts. He said that a new production facility had been established in Ilami (Fig.7) for the mass production of vanes (200,000 and rotors (30,000 pieces/month) pieces/month) from air atomized AI-Si-Fe powders for usc in air conditioning compressors in cars (Fig.S). This photo also shows other hot extruded oil pump rotors produced for racing car engines. and orbital scrolls. The PM aluminium allo\'s have a RT temperature strength of 470 N/~mz and 320 N/mm z at473K said Dr. Takeda. The orbital scroll is produced by a powder forging process. which he said promises to revolutionise the production of PM aluminium components. The scroll is produced at a rate of 'several thousand parts/month' to a tensile strength of 450 N/mm l and fatigue strength of 210.N/mm l at room temperature. It has good machinability after forging with low thermal expansion and high stiffness. stated Dr Takeda. It has already proved successful in trials for domestic air conditioning compressors. Other efforts in the area of PM aluminium includes the mass production of PM AI-40%Si alloys for heat sinks in microw
FIG. 11 IB.\! CAD stations for tool and part design of PM aluminium alloys including dispersion strengthened AI-Si-AI,C1 and AI-Al 10 1 alloys having good thermal fatigue. and good and corrosion electrical conductivity resistance. Potentia) applications include diesel engine parts and electrical conductors for NaS electric car balleries.

OKAYAMA SUl\lIOEN SEIl\lITSU (055)

PM PLANT When MPH last visited this plant set among very pleasant rolling and \\'ooded hills in Nariwa (Fig.9). we were particularly impressed with the high )e\'el productivity with only around 150 people required to produce 340 tonnes/month (46S0 tonnes/year) of structural PM parts. In the intervening 10 years the original plant has been complemented by a second plant in three sections (A. B. and C) to bring total production space to 72.290 m2, and output has meanwhile tripled to an
PM parts per year. and the number of employees has risen to only 390. The le\'el of productivity is an achievement of which the company can be justifiably proud. Mr. Y. Nagasaka. senior managing director of ass explained lhat practically all available production space had now been utilised on the site. and in order to meet increasing demand the company adopted computer integrated manufacturing (CIM) in the 'C' section of Plant 2 which was completed in July 1985. elM has boosted producth·ity by O\'er 250% and lead time has been reduced from 4 days to only 15 hours. said Mr Nagasaka. and was therefore worth the initial high ill\"estment of around Yen 500 million per line. The new plant is 10 the flexible essenlially dedicated manufacturing of monthly orders for a specific range of PM parts which are then delivered in relatively small daily lots of 5,000 to 10,000 parts on a 'just-in-time' basis now favoured by customers in the car industry. The increasing usc of automation has also helped boost producth·ity in older sections of the plant although not to the same extent as in elM. ass operates some SO powder compacting presses ranging in capacity from 5 to SOO tons.

419

STAND 42

_HIP'PED PARTS AND CLADDED COMPONE TS

_SUPERALLOY POWDERS _P.M. SUPERALLOY SEMI-PRODUCTS AND PARTS _HARDFACI G POWDERS _NICKEL, COBALT. IRON BASED POWDER _TITAN! M POWDER META RGY PART

_-------OFFICES 19. e Parvis' E VSEES DEFE SE· Cedex 35 . 92072 PARIS LA DEFE SE· FRAI CE iELEX: 614846 I PHY F· iELEFAX, (33-1) 47.6 .98.85

FIG. 12 One oJtheSodick EDM machines

FIG. 13 Grippers remm'e the compact Jrom the die area to amid pick up oj loose iron pOll'der

FIG. 15 Computer integrated manuJacturing line comprising 4 pOll'der presses Jeeding into a sintering Jurnace and sizing, Parts are transJerred along o\'erhead com'eyors 50 sizing presses in the same range, and 22 sintering furnaces of which 2 are for high temperature sintering. The company has around 2,500 active tools including bearings, although the production of bearings at OSS now forms only a small part of output. The company maintains a powder store of some 250 tonnes of iron and other powders r.quivalent to about a week's production. The powders are sieved before being transferred to the blending station where they are stored in 12 hoppers each containing 3 tonnes of powder. Here an automated and computer controlled facility instaIled some 9 years ago [Fig.l0) accurately weighs and supplies the required powder ingredients to the 1 tonne double cone blender. The blending schedule is determined by the mainframe computer into which the press shop has given details of the grades reqUired for a particular press, in which plant, and at wha! time. Blending is done to the desired apparent density and the container is then bar coded for easy traceability in the planl.The company maintains a relatively smaIl tool section employing 20 people who Produce only around 20% of the new tools but maintain and repair all existing tools. There are three CAD stations [Fig.ll) undertaking

MPR June 1990

component and tool adaptor design. NC tapes prepared by the design office are used to produce the carbide die insert and core rods on a line of modern NC controIled wire erosion and EDM machines [Fig.12). A tour of the older PM plant - production was started on this site in 1974 - revealed the extent to which automation and 100% weight control of powder compacts has been applied even on older presses. Lines ofl00 and 200 ton presses, dominated by Yoshizuka types, were seen compacting the smaller PM parts and here as in other parts of the plant, compacts were mostly picked up off the press (Fig.13) by padded grippers to avoid contamination with iron powders which would occur if parts were simply pushed away from the die area. Mr Mamoru Sugimoto, manager of OSS's engineering department, told MPR that whilst this requires slightly larger ejection strokes it docs give improved quality of compacts. Only three operators are required to supervise the 14 powder presses in this section, and their work includes die setting and inspection. A line of 3 to 40 ton presses was seen producing PM bearings in a small section of this plant with some of the presses reaching up to 50 compacts/minute.

FIG. 14 Computerised setting up oJ tools and press Junctions on a large compacting press at OSS Sintering is done in Yamazaki and Koyo Lindberg furnaces using a mixture of endogas generated from butane with parts hadng been automatically loaded and stacked onto mesh trays at pressing and automaticaIly unloaded from the trays into the conveyor belt furnaces. This section also houses a new IHI Ipsen-Abar vacuum furnace for continuous sintering of Cr-containing steel parts. An interesting concept to avoid damage to sintered bearings has been developed whereby the bearings go through a shallow oil bath before dropping off the furnacr. belt. Larger iron-based bearings are also weight controlled for SPC purposes. In PLANT2Aa further range ofl00 and 200 ton presses was seen producing high strength helical gears, rack and pinion guide rack for powder steering, rotors for power steering, and again automatic weighing linked to SPC and automatic palleting for transfer to com'eyor belt and pusher type sintering furnaces was prm'alenl. Yuken presses are extensively used in this plant for sizing, and the plant also houses four steam treatment furnaces, three heat treatment furnaces, and equipment for shot blasting. PLANT 2B meanwhile houses lines of two 500 ton and two 800 ton hydraulic presses plus 500 ton mechanical presses to produce synchronizer hubs, belt pulleys, large parachoidal inner and outer rotors, etc. Again extensive usc is made of microprocessor technology to control press functions in order to obtain optimum productivity and part quality (Fig.14). One oCthe 800 ton presses was seen compacting a complex multi-Ie\'c\ synchronizer hub with three steps in the top tool and three in the bottom, and another press was seen producing a redesigned and weight saving belt pulley. Tool change on the large presses was said to take around 15 minutes with 1 to 1.5 hours for fine adjustments. One of the features of this plant is the usc of 'musical' robots which are perfectly contented to spend their working day traversing across the compacting lines collecting trays of green compacts from the presses and positioning them onto the belts of four sintering furnace in

421

KY

U NAC

M

TIN

P ES SFE

OBO

W

P FOA OT CO TA L PA ANS I

WEI M

AI G

PC F

ICK U RO

ROBOT

T

ES I

FIG. 16 Schematic diagram of the CIM line at

ass .

a synchronized manner. The robots are musical only when working so as to alert any operators in the area of their movement. Optimum belt loading is achieved by the stacking of parts going through the furnace. Sizing is done on impressive lines of 200.400 and 800 ton presses made by Komatsu. Yuken and Tanaka Came, and a small number of lines arc available for finish machining of synchro hubs (tapping. drilling. burnishing and broaching) followed by induction hardening and resizing. However, the bulk of finish machining is done by a sm subsidiary Tsubasa Seimitsu Ltd. The 'piece de resistance' of OSS is without doubt the new CIM operation in PLANT 2C with one of the CIM lines shown in Fig.15. The lines arc essentially dedicated to the production of a series of PM parts produced in runs from 5,000 to 10,000 pieces with the mainframe computer setting up the daily production quota for just-in-time delivery schedules. As already mentioned the computer coordinates powder blending - it is desirable to usc the same basic grades in CIM - so that the material is available at the designated line on time. The line shown in Fig.15 and schematically in Fig.16 comprises two 200 tOll Yoshizuka powder presses with computerised weight control with robots positionins the compacts accurately onto mesh trays (Fig.17). Robots arc again used to

422

E CON EY A

place the trays onto an overhead pallet conveyor for transfer to the sintering furnace. and after sintering the parts are picked up by robots, separated because of sticking together of the stacked parts. and conveyed to the 200 ton Ohtsuka and Tanaka Came sizing presses. This line is mainly dedicated to the production of parachoidal rotors with controls at every stage of the manufacturing process to ensure 100% quality 1(J\·el. There is another CIM line using 750 ton and 500 ton powder presses to produce larger trochoidal rotor parts at a rate of 800,000 parts/month, and bearings for. compressors at 700,000 per month. This line has in-line steam treatment for improving the air tightness of compressor parts. OSS now plans to add a third CIM facility in this plant which will incorporate high temperature sintering. tomputer integrated manufacturing has enabled productivity increases ofover250% to be achieved, and OSS's impressive CIM lines will undoubtedly become an important model for the PM industry worldwide for some time to come.

QUALITY CONTROL Supporting such first class PM production facilities and to ensure continuing high quality levels, ass operates a routine inspection department for testing of sintered properties, microstructures. and dimensional accuracy (Fig.18). as well as sophisticated equipment at the Itami Research Centre where the

FIG. 17 Robots pickup parts and position them accurately an sintering mesh trays in the CIM

line

performance and properties of the entire range ofsintered products can be evaluated. (F'ig.19). A major feature ofOSS's philosophy on quality are the activities of the Quality Circles which have become so much a part of Japanese manufacturing plants. ass operates 45 QC groups with an average of (j persons per group who meet 1 to 3 times per month for 30 min. to 1 hour to discuss problems in their particular manufacturing environment. Once a month 5

MPR June 1990

paint the floors, clean equipment. arrange tools. etc.. at their own initiative. A weekly patrol of 10 people checks on the cleanliness of the plant. and once a month there is a 5S patrol by the president. directors and managers. In this way. the working environment is kept clean and orderly. enhancing safety. quality and productivity in the plant. PM companies outside of Japan would do well to emulate this system. It is difficult. if not impossible, to find fault with any part of the OSS operation. and MPR certainly looks forward to further illuminating visits in the years to come.

FIG. 18 Production quality control department atOSS QC groups will presentation or management.

combine for a poster discussions with the

The '55' Movement As part of an effort to maintain a pleasant working environment. OSS operates what it calls the '5S Movement' with the 5Ss deriving from the Japanese words: Seiri - Classification or Order Seiton - Arrangement Seiketsu - Cleanliness Seisou - Cleaning Shitsuke - Discipline The objectives of this movement are that 5S meetings are held monthly with the foremen of each section, and members of each section

FIG. 19 Faci/ityat SE/'s Itami Research Centre farperformance testing and em/uating ofPMparts

The ABRA ame stands for many years of experience in esign a d co s rL c(o of isostatic presses fo labora ory and p duc io ABRA IS yo partner f om proole analysis to the i s allatio of your tailor made e IIpmen. ABRA g arantees quality, high perlo mance al d safety. Con ac one of 0 r specialists. ABRA 51 E AG Bosc chs. 117, CH-9443 Widnau/Switzerla d Tel. 71/72 43 51. Fax 71/72 73 55. Tel ,x 882535 abra ch MPR June 1990