compresslw resldual stresses. Laser surface m odltlcatlon
followlng the EDM of dle steel and cemented carblde
workplece materlals has also been reported [20. 211.
Here, mettlng In whole or part, of the orlglnal recast
structure Is employed to provlde a new, apparently defect
free surface. Unfortunately. such processes are addttlonal
to the orlglnal EDM operatlon and therefore add cost and
tlme. An attematlve solutlon Is the controlled alloylng of
the rmrkplece surface durlng sparklng wlth metal powders
dlspersed In the dlelectrlc, In a slmllar manner to that
detalled previously, to produce a pollshed surface
appearance, or the use of partlally slntered electrodes,
typlcally made from refractory metal powders and a blnder.
Netther Is mutually exclusive and thelr slmuttaneous use
owers the prospect for harder more war reslstant surfaces
wlth low roughness and mlnlmal cracklng. The use of the
recast structure In a modMed form to promote the jolnlng
of materlals Is also a posslblllty. Flgure 1 shows
schematlcs of both arrangements.
2 SURFACE ALLOYING
Perhaps not surprlslngly, publlcatlons detalllng the use of
powders suspended In the dlelectrlc for workplece surface
alloylng, to a large extent reflect the approach and
technology employed for the produdlon of pollshed
surfaces [2, 22-25]. Wch of the work relates to steel
workpleces wlth a kerosene dleledrlc (to provide pyroiytlc
C) and Cu tool electrodes, although the posslblllty of uslng
graphtte tools Is also acknowledged. An lllyarse or reverse
polartty arrangement Is universally recommended (-ve Cu
electrode). The types of powder employed dmer
somewhat from those prevlously detalled and Include In
the maln W, NI, TI. Co. Fe, Mo and Mn, wlth quoted graln
shes between -1-100 pm, although tt Is suggested that
partlcles >50pm can obstruct the gap and dlsrupt the
process [2]. Uno et a1 [22] detall the modltlcatlon of an
alumlnlum bronze workplace used In shell mouldlng Ath a
NI powder / kerosene dlelectrlc mix. The spark gap
dlstance Is shown to Increase substantlally as the NI
@I
Flgure 1: Schematlc of surface alloylng wlth (a) PM
electrodes; and @] powder suspenslon (w powder shown).
compresslw resldual stresses. Laser surface m odltlcatlonfollowlng the EDM of dle steel and cemented carbldeworkplece materlals has also been reported [20. 211.Here, mettlng In whole or part, of the orlglnal recaststructure Is employed to provlde a new, apparently defectfree surface. Unfortunately. such processes are addttlonalto the orlglnal EDM operatlon and therefore add cost andtlme. An attematlve solutlon Is the controlled alloylng ofthe rmrkplece surface durlng sparklng wlth metal powdersdlspersed In the dlelectrlc, In a slmllar manner to thatdetalled previously, to produce a pollshed surfaceappearance, or the use of partlally slntered electrodes,typlcally made from refractory metal powders and a blnder.Netther Is mutually exclusive and thelr slmuttaneous useowers the prospect for harder more war reslstant surfaceswlth low roughness and mlnlmal cracklng. The use of therecast structure In a modMed form to promote the jolnlngof materlals Is also a posslblllty. Flgure 1 showsschematlcs of both arrangements.2 SURFACE ALLOYINGPerhaps not surprlslngly, publlcatlons detalllng the use ofpowders suspended In the dlelectrlc for workplece surfacealloylng, to a large extent reflect the approach andtechnology employed for the produdlon of pollshedsurfaces [2, 22-25]. Wch of the work relates to steelworkpleces wlth a kerosene dleledrlc (to provide pyroiytlcC) and Cu tool electrodes, although the posslblllty of uslngนอกจากนี้ยังมีการยอมรับเครื่องมือ graphtte Lllyarse การย้อนกลับจัด polartty แบบแนะนำ (-ve Cuอิเล็กโทรด) ชนิดของผงจ้าง dmerจากนั้น prevlously detalled และรวมในค่อนข้างmaln W, NI ตี้ บริษัท Fe, Mo และ Mn, wlth เสนอราคา gralnแหกปากระหว่าง -1-100 น. ถึงแม้ว่า tt แนะนำที่partlcles > 50 น.สามารถกั้นช่องว่างและ dlsruptกระบวนการ [2] อูโน่ร้อยเอ็ด a1 [22] detall modltlcatlon ของการใช้เปลือก mouldlng Ath ทำ alumlnlum ทองมีผง NI / dlelectrlc น้ำมันก๊าดผสม ช่องว่างจุดประกายแสดงการเพิ่ม substantlally เป็น NI dlstance@IFlgure 1: Schematlc ของผิว alloylng wlth (แบบ) น.หุงต และแอท] suspenslon ผง (ผง w ที่แสดง)
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