PM Part Production atNihon Funmatsu Gokin

Nihon Funmatsu Gokin KK (tran slated Jap anPowder Metallurgy Ltd) is on e of Jap an'smedium si ze PM part producers w ith two PMplants - on e in Yarnashina, near Kyoto,comprising some 9,302 m2 production space ­and the other is a new er plant ofs ome 7,120 m2

production space on a large (59,000 m2) s ite atSiga. A total of 500 people are employed at bothplants.Mr Kunizo Imanishi, president of NihonFunrnatsu, and until May 1990 president of theJapan Powder Metallurgy Association, statedthat his c ompany ach ieved approximately 5%growth in 1989 with monthly shipments of PMparts and bearings rising to an average ofaround 500 tonnos. This equates to some 27million parts permonth. Total sales for fiscal19 89 were Yen 10.2 billion.Mr Iman ish i told MPH that there are currentlysome 1200 different typ es of PM componentsin production with 72% of output going to th eautom ot ive industry - th e company is now10 % owned by Toyota Motor Corp.- with afurther 12 % for industrial applications. 9% forelectrical materials . and 7% for frictionmaterials.

In terms of automotive parts , Nihon Funrnatsuis probabl y one of Japan's largest producers ofs in tered valve seat inserts with annualshipments during 1989 said to exce ed 40mill ion pieces. There are sa id to be some 50d ifferent types of inserts in production us ingfive types of ferrous based powders includinghigh-sp eed st eel and stainless steel. Thecompany also reports a significant increase inproduction of high strength PM parts such asshift levers and synchronizer rings. outerrotors of power steering pumps. etc .The range of soft magnetic. components hasbeen expanded with pure iron.iron-phosphorus. iron-silicon, iron-nickel andcorrosion resistant 410 and 430 stainless steelsiron-chromium alloys used to producemagnets for relays, yokes , st ators , pol e pi eces,etc (Fig.1) . Close tolerances are achieved in thesintcrcd material thereby el im in ating the needfor secondary machining.Sintered friction mat erials (Fig.2) such asbrake and clutch linings have been a feature ofthe company's production capabilities formany years, and the company has ach ievedconsiderable success in producing th ese for

the automotive industry and for heavy dutyapplications suc h as the brake lining on th ehigh speed Shinkan sen ex press train wh ich arerequired to have ex treme ly high energyabsorbing capacity. Frict ion materials a remad e from mixtures of bronze-c eramic­graphite wh ich are compac ted on presses up to800 tons capaci ty followed by diffusionbonding of th e compacts onto backing platesduring sintering under pressure at 800C.Friction materials are also produced for clutchlinings us ed on trucks, buses . tractors, cars , e tc.and are made from copper- and iron-basemateri al s.OneofNihon Fu nrnatsu 's first PM componentswas the cur rent collector sliders used on th epantographs of electric locomotives , subwaycars, and tod ay al so on the high speedShinkanson tra ins . Th e sliders are mad e fromiron- or copper- based alloys into which isincorporated a solid lubricant which ensuresthat contact res istance with the electric wire isvery low. thereby reducing erosion without adecrease in voltage. A vari ety of slider materialgrades are in production ranging in sintercddensity in the copper-base alloys from 7.6 to8.4 g/cm" and hardness of up to 95 HB. Aniron-base alloy is also in production for use onShinkan sen trains which has a density of6.7-6.9 g/crn", ha rdness of 65-95 HB. andtensile stren gth of 196 Nzrnrn ".Stainless steels and high speed steels havemaintained an important place in th eproduction programme at Nihon Funmatsuwith a range of austenitic (304 and 316) and

./? :J/ ., J .' .<, . ,' ,

r '- ' ;"..FIG.1S election ofsoft magnetic structural parts in production at NihonFunmatsu Gokin

FIG. 3 Selection ofstainless steel PM parts

MPR June 1990

FIG. 2 Sintered friction mat erials used in brakes

FIG. -1 Control centre for powder mixing

481

"FIG. 5 Line of500kg capacity V-type powder blenders

right way up before machining and grinding ofthe 'taper angle. chamfer, diameter and partthickness. They are then cleaned and passedthrough an optical check where camera lensessend the image of each insert to a computer inorder to ensure that the insert has no surfaceflaws by calculating the surface area. Theselines, which were entirely developedin-house, have allowed the company to greatlyimprove the productivity of finishing valveseat inserts without any sacrifice in quality.Mr Imanishi (Fig. 7) told MPR that the powdermetallurgy process still had an inherentweakness in terms of total part reliability. andit was therefore necesssary for the PM partproducer to introduce such sophisticatedquality control testing. However. he believedthat the reliability of PM parts could be greatlyimproved without such high cost inspectionby improving the consistency and quality ofthe metal powders used. Ifthis can be achievedthe PM parts industry could see output doublein the years ahead, he said. A selection of PMparts in production at Nihon Funmatsu isshown in Fig.8

"FIG. 6 One of the nell' machining/inspection lines for the finishing of valve seat inserts

• •

FIG. 8 Selection of PM parts in production atNihon Funmatsu

FIG. 7 Mr Kunizo Imanishi, president ofNih onFunmatsu Gokin

V-type mixers (Fig.5).The company now operates a total of 92powder compacting presses, 83 of which ofwhich are mechanical with the largest being an800 ton hydraulic press for compacting brakelinings, and the smallest 3 ton presses used forcompacting self lubricating bearings. Anumber of 60 ton ten station rotary powdercompacting presses are used for the pressing ofvalve seat inserts with each machine capable ofproducing more than 1 million inserts permonth. There are additionally 61 sizingpresses ranging in capacity from 2 to 500 tons,and 26 sintering furnaces (conveyor andpusher type) arc used with many havingseveral layers ofPM parts being fed through thefurnace to improve productivity.With valve seats now making up a sizeableproportion of PM part production, thecompany has installed four new fullyautomatic machining and inspection lines toguarantee the quality of all inserts that leavethe Yamashina plant. Sized valve seat insertsare loaded into the inspection line (Fig.6), andare first checked that they have been loaded the

PM PRODUCTION

In 1985 the Yamashina PM plant introduced anew computerised blending facility to copewith the 200 mixes which the company has toregularly produce. Details of each mix arestored on a computer and the operator has onlyto request a particular grade (FigA) and thecomputer will then select the ingredients fromsome 40 storage vessels each containing 500 kgof powder which are then fed into a line of

martensitic (410) used for structural parts asshown in Fig.3. High speed steel componentsand other parts requiring high wear resistance,are made from water atomized powders whichare compacted and sintored in vacuumfurnaces. Hardness values approaching 1,000HV in the heat treated condition are beingobtained for one of the company's grade - K6 ­which is based on Fe-4Cr-3Mo-9W-3V-l0Co­1.1/1.3C. This is said to be equivalent to JISgrade SKH57. Applications for PM high speedsteel include vanes for oil pumps, rocker armtips, sealing rings, cams and cam rings, etc.

482 MPR June 1990