MAK­ING A CASE

World of Watches (Singapore) - - Features -

Agreat move­ment is noth­ing with­out a case to pro­tect it – and ev­ery­thing else – from the rav­ages of the out­side en­vi­ron­ment. Of course, de­tails such as wa­ter re­sis­tance and a scratch­proof sap­phire crys­tal are non-ne­go­tiable. How­ever, the choice of ma­te­rial and pro­duc­tion tech­nique for the case are less clear cut given the per­mu­ta­tions of the avail­able op­tions.

Met­als and coat­ings

By elim­i­nat­ing pre­cious met­als like gold and plat­inum, as well as ex­otic ones such as tan­ta­lum, only stain­less steel and ti­ta­nium are left when it comes to me­tal­lic cases. Both are avail­able in sev­eral vari­ants. Grade 2 ti­ta­nium, for in­stance, is close to steel in terms of its hard­ness, but it is far less dense, and there­fore much lighter. Grade 5 ti­ta­nium, on the other hand, is sig­nif­i­cantly harder than its Grade 2 sib­ling and just as light, but lacks the lat­ter’s unique drab grey ap­pear­ance.

Both steel and ti­ta­nium cases can be tough­ened with a di­a­mond-like car­bon (DLC) coat­ing ap­plied via phys­i­cal vapour de­po­si­tion (PVD), which sig­nif­i­cantly in­creases their sur­faces’ hard­ness. This is com­monly done nowa­days for both prac­ti­cal and aes­thetic rea­sons, and its only draw­back is per­haps the hassle and costs of re­pair­ing a chipped/dam­aged coat­ing – the orig­i­nal layer of DLC must be com­pletely stripped be­fore the case is pol­ished and a new coat­ing is reap­plied.

Ex­otic stuff

In­stead of steel or ti­ta­nium, ce­ram­ics and car­bon can also be used to make a watch’s case. These ma­te­ri­als vary in hard­ness and den­sity, but gen­er­ally ex­hibit a high level of tough­ness with a touch of the ex­otic. Ce­ram­ics are fairly straight­for­ward – com­pact the pow­dered for­mu­la­tion in a mould, bake it un­der high pres­sure to sin­ter it into a solid, then ma­chine this mass to cre­ate a fin­ished case. Car­bon, on the other hand, can be forged, baked, or vac­uum-moulded to­gether, of­ten with other “in­gre­di­ents” such as quartz fi­bres to en­hance its prop­er­ties. The last step is still ma­chin­ing though, to achieve the de­sired shape and con­tours.

New pro­duc­tion tech­niques

The avail­able ma­te­ri­als de­scribed above are fairly well un­der­stood, and new ones be­ing in­tro­duced tend to be vari­a­tions on ex­ist­ing themes, with mar­ginal im­prove­ments over cur­rent of­fer­ings. New pro­duc­tion tech­niques, how­ever, some­times cre­ate par­a­digm shifts. Di­rect Metal Laser Sin­ter­ing (DMLS), for ex­am­ple, was in­tro­duced by Pan­erai ear­lier this year in its Lo Scien­zi­ato Lu­mi­nor 1950 Tour­bil­lon GMT Ti­tanio PAM578. The tech­nique is al­ready in use else­where, in­clud­ing the aero­space and med­i­cal in­dus­tries, and works just like 3D print­ing – a solid com­po­nent is “built” from a metal pow­der us­ing a laser, which sin­ters the pow­der layer by layer. Un­like sub­trac­tive pro­duc­tion, which in­volves re­mov­ing ma­te­rial by cut­ting/milling out un­wanted parts, DMLS is ad­di­tive, and ca­pa­ble of pro­duc­ing solid com­po­nents with hol­low in­te­ri­ors. As the PAM578 shows, a hol­low ti­ta­nium case can be made with DMLS, with no loss of struc­tural strength or wa­ter re­sis­tance thanks to the ma­nip­u­la­tion of the in­ter­nal space’s shape.

|| THE VER­DICT ||

The clear win­ner here is the lat­est and great­est tech­nol­ogy avail­able – DMLS. Ti­ta­nium, es­pe­cially its Grade 5 vari­ant, is al­ready light and hardy enough to stand up to gen­eral abuse. With DMLS, fur­ther weight sav­ings can be had for an ex­tremely com­fort­able chronograph with no loss of strength.

Aude­mars Piguet Royal Oak Off­shore Diver chronograph in steel, with ceramic push­ers

Bul­gari Octo Ve­locis­simo Ul­tranero Pan­erai PAM578 Oris Wil­liams Chronograph Car­bon Fi­bre Ex­treme

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