Amachinescrew, Alsosometimesreferredtoasamachinebolt, isascrewthatistypicallydesignedtobe
fastenedtoanexisting, tappedholeonametalsurface, usuallyinconjunctionwithacorrespondingnut.
Thesetypesofscrewsarenotaslargeastheaveragescrew, usuallyranginginsizesuptothreequarters
ofaninch (19,05 mm) buttheycanstillbelarger.Variationsbetweenmachinescrewsmainlyexistinoverall
koko, shapeofthehead, slottype, pituus, materiaali, andcharacteristicsofthethread.
Amajorwayofcategorizingamachinescrewisbythetypeofslotinthehead, whichwilldeterminethekind
ofscrewdriverthatistodriveitintoitshole.Thetwomajorkindsofscrewdriversusedwithmachinescrews
areslottedandPhillipsheadscrewdrivers, butthereareseveralotherminortypesofscrewdriveholessuch
asTorxsix huomautti, tähti-shapeddriveholesthatrequiremorespecializedscrewdrivers.Specialized
tyyppisiä ruuvinruuvia, joissa voi olla merkitystä, kun ruuveja ei anneta
safetyreasons, sinceitismoredifficulttoacquirespecializedtypesofscrewdrivers.Adangerouselectrical
paneeli, forinstance, isagoodplaceforamachinescrewwithaspecializedtypeofhole.Othermachinescrew
headscanbesimilartoahexorsquareboltthathavenoscrewdriverslotandmustbeturnedwithawrench.
Theshapeoftheheadofamachinescrewwilldeterminehowitliesonceitisfastenedtoahole.Roundand
panheadswillprotrudefromaflatsurfaceoncetheyareattached.Flat-headedscrewsaredesignedforholes
thatareboredsotheylayflushwiththesurfacewhentheyhavebeenscrewedin.Theheadofasetmachine
screwissmallerthanthediameterofthescrewthreads, sowhenitisattacheditcanbedriventhroughahole
andadjustedtoadesireddepth.
Moreofthemajordifferencesbetweenmachinescrewsareinthecharacteristicsofthethread.Thispartof
anygivenmachinescrewisoneofthemostimportant, becausethecorrespondingholesthattheyare
fastenedtowilltypicallybetappedtofitonlyonespecificsizeandtypeofscrewthread.Thesystemusedfor
characterizingdifferentthreadsusuallyfollowsISO (InternationalOrganizationforStandardization) standardit,
whichhavebeenestablishedtokeepconsistentdesignspecificationsinmachinepartsproducedthroughout
theworld.Twoofthemajorthreadcharacteristicsareitsdiameterandpitch, thelatterbeingthedistance
betweenthreads.Thesescrewthreadscanalsobemadetobescrewedclockwise (oikeakätinen) tai
vastapäivään (vasenkätinen).
Whilethesizeofamachinescrewisusuallyrelativelysmall, therecanstillbeavastamountofvariations
betweensize, shapeandlength, mostlydeterminedbytheirintendedpurposeandhowstrongtheyneedtobe.
Pringmetal pystyy tuottamaan useimpia koneen ruuveja jo edellä mainituista, myös Tyylikkäät ruuvit voivat myös olla valmistettuja erityisiä koneita, jotka on tarkoitettu käytettäväksi aina seuraavalle
ISOstandards.Machinescrewscanbemadeofanyofavarietyofmetalsorplastics.