Deunyddiau Gwydn

Resistant Materials

Mae deunyddiau gwydn yn gallu gwrthsefyll plygu a dirdroi, felly mae angen offer llaw a pheiriannau i’w torri a’u siapio.

Y deunyddiau gwydn a gaiff eu dosbarthu a’u defnyddio at ddibenion dylunio a thechnoleg yw metelau, pren, plastigion a deunyddiau smart.

Metel

Caiff metelau eu dosbarthu fel a ganlyn:

  • metelau fferrus neu anfferrus;
  • aloeon a
  • metelau smart.

Metelau fferrus yw metelau sy’n cynnwys haearn, h.y. haearn a dur.

Metelau anfferrus yw metelau nad ydynt yn cynnwys haearn, h.y. pob metel heblaw haearn a dur.

  • Ceir metelau pur megis copr ac alwminiwm. Nid yw’r rhain wedi cael eu cyfuno â dim byd arall, felly nid yw eu priodweddau wedi eu newid gan ychwanegu unrhyw elfen arall.
  • Ni chaiff metelau pur eu defnyddio’n aml ar gyfer cynhyrchion gweithgynhyrchu oherwydd gellir gwella eu priodweddau a’u nodweddion gwaith drwy eu cyfuno â deunyddiau eraill i gynhyrchu aloeon metel mwy defnyddiol.

Aloeon metel yw cymysgeddau o fwy nag un metel, neu gymysgeddau o elfen fetel ac anfetelau.

Un o’r aloeon a ddefnyddir amlaf yw dur, sef aloi o haearn a charbon.

  • mae dur meddal yn cynnwys hyd at 0.25% carbon,
  • mae dur carbon canolig yn cynnwys rhwng 0.25% a 0.7% carbon ac
  • mae dur carbon uchel yn cynnwys rhwng 0.7% ac 1.5% carbon.

Mae aloeon dur eraill yn cynnwys cymysgeddau o haearn ac elfennau eraill megis manganîs, molybdenwm, nicel, cromiwm, twngsten, silicon a fanadiwm.

  • Mae efydd yn aloi o gopr a thun
  • Mae pres yn aloi o gopr a sinc
  • Mae aloi alwminiwm yn cynnwys alwminiwm, copr, sinc, manganîs a silicon

Metelau smart yw metelau sy’n adweithio i ysgogiadau penodol ac yn newid eu siâp.

Pren

Gellir dosbarthu pren fel a ganlyn:

  • pren caled neu bren meddal;
  • coed naturiol neu bren cyfansawdd.

Nid oes gan yr enwau pren caled a phren meddal ddim i’w wneud â pha mor galed neu feddal yw’r pren.

  • Pren caled yw pren a gynhyrchir o goed collddail llydan-ddeiliog./li>
  • Pren meddal yw pren a gynhyrchir o goed conwydd â dail nodwydd.

Pren cyfansawdd yw llenni o ddeunydd pren megis bwrdd ffibr dwysedd canolig (MDF) a wneir o bren wedi’i brosesu.

Mantais pren cyfansawdd dros blanciau o bren yw eu bod yn cael eu cynhyrchu mewn byrddau mawr o drwch cyfartal. Gwneir y byrddau o amrywiaeth o ddeunyddiau megis llwch pren mân wedi’i fondio fel yn MDF, sglodion pren mwy wedi’u bondio fel mewn bwrdd sglodion, argaenau wedi’u bondio fel mewn pren haenog neu gyfansawdd wedi’i fondio o estyll ac argaenau fel mewn blocfwrdd.

  • Gellir cael pren cyfansawdd â gwahanol briodweddau sy’n addas at amrywiaeth o ddibenion, o adeiladu i greu awyrennau.
  • Mae’r adlynion a ddefnyddir mewn pren cyfansawdd hefyd yn amrywio, o rai sy’n hydawdd mewn dŵr i rai cwbl wrth-ddŵr fel a geir mewn pren haenog gradd morol.

Plastigion

Gellir dosbarthu plastigion fel a ganlyn:

  • thermoblastigion neu thermosetiau;
  • polymerau smart.
  • Thermoblastigion yw plastigion y gellir eu meddalu gyda gwres.
  • Thermosetiau yw plastigion na ellir eu meddalu gyda gwres.

Polymerau smart yw plastigion sy’n ymateb i ysgogiadau ac yn newid eu siâp.

Resistant materials are materials that resist bending and twisting, therefore hand and machine tools are required to cut and shape them.

The resistant materials that are classified and used for design and technology are metals, wood, plastics and smart materials.

Metal

Metals are classified as:

  • ferrous metals or non-ferrous metals;
  • alloys and
  • smart metals.

Ferrous metals are metals that contain iron, i.e. iron and steel.

Non-ferrous metals are metals that do not contain iron, i.e. all metals other than iron or steel.

  • There are pure metals such as copper and aluminium. These have not been combined with anything else, so their properties have not been changed by the addition of any other element.
  • Pure metals are not often used for manufacturing products because their properties and working characteristics may be improved by combining them with other materials to produce more useful metal alloys.

Metal alloys are mixtures of more than one metal, or are mixtures of a metal element and non-metals.

One of the most commonly used alloys is steel, which is an alloy of iron and carbon.

  • mild steel has up to 0.25% carbon,
  • medium carbon steel has from 0.25% - 0.7% carbon and
  • high carbon steel has 0.7% - 1.5% carbon.

Other steel alloys include mixtures of iron and other elements such as manganese, molybdenum, nickel, chromium, tungsten, silicon and vanadium.

  • Bronze is an alloy of copper and tin
  • Brass is an alloy of copper and zinc
  • Aluminum alloy contains aluminum, copper, zinc, manganese and silicon

Smart metals are metals that react to certain stimuli and change their shape.

Wood

Wood can be classified as:

  • hardwood or softwood;
  • natural timber or manufactured board.

Hardwoods and softwoods have nothing to do with how hard or soft a wood is.

  • Hardwoods are timber produced from deciduous trees that have broad leaves.
  • Softwoods are timber produced from coniferous trees that have needle-like leaves.

Manufactured boards are sheets of wooden material such as medium density fibreboard (MDF) made from processed timber.

The advantage of manufactured boards over timber planks is that they are produced in large boards of even thicknesses. Boards are made from a variety of materials such as bonded fine wood dust as in MDF, bonded larger wood chips as in chip board, bonded veneers as in plywood and a bonded composite of battens and veneers as in blockboard.

  • Manufactured boards come in different qualities suitable for a range of applications, from construction to aircraft building.
  • The adhesives used in manufactured boards also vary, from water soluble to totally water proof as in marine grade plywood.

Plastics

Plastics can be classified as:

  • thermoplastics or thermosets;
  • smart polymers.
  • Thermoplastics are plastics that can be softened by heat.
  • Thermosets are plastics that cannot be softened by heat.

Smart polymers are plastics that react to stimuli and change their shape.