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Sunday, April 13, 2008
Tuesday, March 18, 2008
BAHAN KEJURUTERAAN - PLASTIK
http://ms.wikipedia.org/wiki/Plastik
PLASTIK
Dari Wikipedia Bahasa Melayu, ensiklopedia bebas.
Istilah plastik merangkumi produk polimer sintetik atau semi-sintetik. Ia terbentuk daripada kondensasi organik atau penambahan polimer dan boleh juga terdiri daripada bahan lain untuk meningkatkan ketahanan atau ekonomi. Ada beberapa polimer alami yang termasuk plastik. Plastik dapat dibentuk menjadi filem atau gentian sintetik.
Nama ini berasal daripada fakta bahawa banyak daripada mereka dapat dilentur, memiliki sifat keplastikan. Plastik direka dengan kepelbagaian yang sangat banyak dalam ciri-ciri yang dapat menahan panas, keras, kebergantungan dan lain-lain. Digabungkan dengan kemampuan adaptasinya, komposisi yang umum dan beratnya yang ringan memastikan plastik digunakan hampir di seluruh bidang industri. Plastik dapat juga menuju ke setiap barang yang memiliki ciri-ciri yang deformasi atau gagal kerana ketegangan(lihat keplastikan (fizik) dan mulur).
Plastik dapat dikategorikan dengan banyak cara tapi paling umum dengan melihat tulang-belakang polimernya (vinilklorida}, polietilena, akrilik, silikon, uretana, dll.). Pengkelasan lainnya juga umum. Plastik adalah polimer; rantai-panjang atom mengikat satu sama lain. Rantai ini membentuk banyak unit molekul berulang, atau "monomer".
Plastik yang umum terdiri dari polimer karbon saja atau dengan oksigen, nitrogen, klorin atau belerang di tulang belakang. (beberapa minat komersial juga berdasar silikon). Tulang-belakang adalah bahagian daripada rantai di jalur utama yang menghubungkan unit monomer menjadi satu. Untuk mengetahui ciri-ciri plastik kumpulan molekul berlainan bergantung daripada tulang belakang (biasanya "digantung" sebagai baghaian dari monomer sebelum menyambungkan monomer bersama untuk membentuk rantai polimer). Penghasilan oleh kumpulan rantaian ini telah membuat plastik menjadi bahagian tak dapat dipisahkan dalam kehidupan abad ke-21 dengan memperbaiki ciri daripada polimer tersebut. Pengembangan plastik berasal daripada penggunaan bahan semula jadi (seperti: karat, "shellac") hingga ke bahan yang diubahsuai secara kimia (seperti: karat semula jadi, "nitrocellulose") dan akhirnya ke molekul buatan-manusia (seperti: epoksi, polivinil klorida - PVC, polietilena).
Diambil daripada "http://ms.wikipedia.org/wiki/Plastik"
BAHAN PLASTIK
Material plastik dapat dibagi menjadi 2,
- Thermoplastik
- Thermoset
Material plastik yang paling penting:
- Polypropylene(PP) - karpet
- Polyvinyl chloride(PVC) - paip
- High Density Polyethilene(HDPE) - botol
- Linear Low Density Polyethilene(LLDPE) - filem
- Low Density Polyethylene(LDPE) - filem
- Polyester, thermoplastic(PETE) - botol minuman ringan
- Polystyrene(PS) - kaset
- Phenolic - lem plywood
PLASTIK
Dari Wikipedia Bahasa Melayu, ensiklopedia bebas.
Istilah plastik merangkumi produk polimer sintetik atau semi-sintetik. Ia terbentuk daripada kondensasi organik atau penambahan polimer dan boleh juga terdiri daripada bahan lain untuk meningkatkan ketahanan atau ekonomi. Ada beberapa polimer alami yang termasuk plastik. Plastik dapat dibentuk menjadi filem atau gentian sintetik.
Nama ini berasal daripada fakta bahawa banyak daripada mereka dapat dilentur, memiliki sifat keplastikan. Plastik direka dengan kepelbagaian yang sangat banyak dalam ciri-ciri yang dapat menahan panas, keras, kebergantungan dan lain-lain. Digabungkan dengan kemampuan adaptasinya, komposisi yang umum dan beratnya yang ringan memastikan plastik digunakan hampir di seluruh bidang industri. Plastik dapat juga menuju ke setiap barang yang memiliki ciri-ciri yang deformasi atau gagal kerana ketegangan(lihat keplastikan (fizik) dan mulur).
Plastik dapat dikategorikan dengan banyak cara tapi paling umum dengan melihat tulang-belakang polimernya (vinilklorida}, polietilena, akrilik, silikon, uretana, dll.). Pengkelasan lainnya juga umum. Plastik adalah polimer; rantai-panjang atom mengikat satu sama lain. Rantai ini membentuk banyak unit molekul berulang, atau "monomer".
Plastik yang umum terdiri dari polimer karbon saja atau dengan oksigen, nitrogen, klorin atau belerang di tulang belakang. (beberapa minat komersial juga berdasar silikon). Tulang-belakang adalah bahagian daripada rantai di jalur utama yang menghubungkan unit monomer menjadi satu. Untuk mengetahui ciri-ciri plastik kumpulan molekul berlainan bergantung daripada tulang belakang (biasanya "digantung" sebagai baghaian dari monomer sebelum menyambungkan monomer bersama untuk membentuk rantai polimer). Penghasilan oleh kumpulan rantaian ini telah membuat plastik menjadi bahagian tak dapat dipisahkan dalam kehidupan abad ke-21 dengan memperbaiki ciri daripada polimer tersebut. Pengembangan plastik berasal daripada penggunaan bahan semula jadi (seperti: karat, "shellac") hingga ke bahan yang diubahsuai secara kimia (seperti: karat semula jadi, "nitrocellulose") dan akhirnya ke molekul buatan-manusia (seperti: epoksi, polivinil klorida - PVC, polietilena).
Diambil daripada "http://ms.wikipedia.org/wiki/Plastik"
BAHAN PLASTIK
Material plastik dapat dibagi menjadi 2,
- Thermoplastik
- Thermoset
Material plastik yang paling penting:
- Polypropylene(PP) - karpet
- Polyvinyl chloride(PVC) - paip
- High Density Polyethilene(HDPE) - botol
- Linear Low Density Polyethilene(LLDPE) - filem
- Low Density Polyethylene(LDPE) - filem
- Polyester, thermoplastic(PETE) - botol minuman ringan
- Polystyrene(PS) - kaset
- Phenolic - lem plywood
Bahan-bahan untuk membuat plastik:
1. Additive
- Antioksidan: mencegah oksidasi yang memutus rantai polimer
- Agen antistatik: menarik kelembaban permukaan supaya konduktif
- Pewarna: memberi warna atau efek seperti iluminasi
- Coupling agents: memudahkan untuk menempel ke bahan lain
- Curing agents: mempermudah penggabungan monomer kepolimer
- Flame retardants: mempersulit plastik terbakar
- Foaming/blowing agents: memberi gelembung udara atau foam
- Penstabil panas: mengurangi pemecahan polimer karena panas
- Penstabilan benturan: menguatkan plastik dari benturan
- Pelumas: mengurangi gesekan plastik keperalatan dan tidak lengket
- Nucleating agents: membantu pengkristalan polimer
- Plasticizer: menambah fleksibilitas, menurunkan titik leleh, dan encer
- Pengawetan: menjaga dari mikroorganisme
- Pembantu proses: menaikkan produksi, memperbaiki permukaan (anti lengket)
- Penstabil UV: mengurangi kerusakan akibat sinar Ultra Violet2.
2. Reinforcement
Bahan yang ditambahkan ke resin dan polimer untuk menambah kekuatan, daya tahan terhadap lenturan, dan kekerasan plastik.Reinforcement dibagi menjadi 2:
- Lamina: memberi lapisan seperti fiber glas, kain, atau lembaran material sehingga menjadi seperti roti sanwidch.
- Fibrous: mencampur dengan beberapa bahan seperti serat kaca, carbonaceous, serat polymer, serat inorganic, serat logam, dan serat hybrids.
3. Filler
Digunakan untuk mengisi sela-sela polimer dan mengurangi harga, tetapi kadang-kadang harga filler lebih mahal dari polimer.
Keluarga plastik juga merupakan bahan-bahan yang dibuat dari bahan petrokimia. Keluarga plastik terbahagi kepada 2 jenis.
Termoplastik [Thermo Plastic]
SIFAT
- Boleh diacu (dibentuk) berulang kali melalui proses pemanasan dan penyejukan.
- Tidak tahan haba
CONTOH (KEGUNAAN)
Politena untuk membuat beg plastik.
Polisterina untuk membuat bekas makanan sejuk (Ta Pau).
Polivinil Klorida/PVC untuk membuat paip air.
Termoset [Thermoset Plastic]
SIFAT
- Boleh diacu hanya sekali sahaja.
- Tahan haba.
CONTOH (KEGUNAAN)
Bakelit untuk membuat soket elektrik.
Melamina untuk membuat pinggan mangkuk.
Gam Epoksi untuk membuat gam industri.
MASALAH PENCEMARAN
Kedua-dua polimer sintetik diatas tahan lama dan tidak mudah mereput [Non Biodegradable]. Oleh itu ia sangat mencemarkan alam sekitar jika tidak diurus dengan baik. Pencemaran yang berasal dari polimer sintetik menyebabkan :
- Longkang tersumbat yang seterusnya mengakibatkan banjir kilat serta pembiakan nyamuk.
- Kehidupan laut mati. Penyu yang menyangka bahan plastik adalah makanan boleh menyebabkan ia tercekik dan mati. Hidupan laut yang berharga itu akan pupus.
- Pencemaran udara. Apabila bahan plastik dibakar ia akan menghasilkan gas toksik (beracun). Gas toksik ini menyebabkan penyakit seperti kanser. Gas ini juga menyebabkan penipisan lapisan ozon.
Pembuangan serta penggunaan polimer sintetik perlu diurus dengan baik. Antara langkah-langkah yang boleh dilakukan adalah seperti :
Kitar Semula. Semua polimer sintetik yang telah digunakan boleh dibawa kekilang untuk diproses semula kepada bahan yang berguna. Beg plastik boleh diguna semula.
Menghadkan penggunaan plastik serta memilih untuk menggunakan bahan yang mudah "terbiodegradasi" (mereput jika dibuang) seperti kertas. Kerusi kayu boleh menggantikan kerusi plastik.
Membakar bahan plastik dalam insinerator [Incinerator] supaya gas toksik yang dikeluarkan dapat dikurangkan.
KEPENTINGAN POLIMER DALAM KEHIDUPAN MANUSIA
Walaupun polimer sintetik telah dikenalpasti sebagai bahan pencemar ia memainkan peranan yang penting dalam kehidupan manusia. Ia merupakan satu pilihan dalam pembuatan bahan yang tahan lama dan dengan ini sangat murah. Ciri-ciri istimewanya seperti ringan telah menyebabkan terciptanya alat-alat seperti baldi, pasu bunga dan kerusi yang mesra pengguna. Oleh kerana negara kita menghasilkan bahan petroleum maka industri petrokimia telah menyumbangkan kepada pendapatan negara. Industri hiliran yang berasasaskan polimer sintetik penting dan telah dikenalpasti sebagai penyumbang kepada ekspot negara. (sumbangan http://www.oasis4.netfirms.com/b57.html)
Friday, February 15, 2008
BAHAN KEJURUTERAAN - LOGAM
Logam
Dari Wikipedia Bahasa Melayu, ensiklopedia bebas.
Lompat ke: navigasi, gelintar
Dalam bidang kimia, logam adalah sejenis unsur yang bersedia untuk membentuk ion (kation) dan mempunyai ikatan logam. Logam-logam biasanya diterangkan sebagai sebuah kekisi ion-ion positif (kation) yang dikelilingi awan-awan elektron tak setempat. Logam adalah satu daripada tiga kumpulan unsur yang dikenalpasti melalui sifat-sifat pengionan dan ikatan, yang lainnya adalah metaloid dan bukan logam. Di dalam jadual berkala, satu garis pepenjuru yang dilukir daripada boron (B) kepada polonium (Po) membezakan logam dan bukan logam. Unsur-unsur pada garis ini adalah metaloid, kadang kala dipanggil ala logam; unsur-unsur ke sebelah bawah kiri merupakan logam-logam, manakala sebelah atas kanan adalah bukan logam.
bacaan seterusnya KLIK SINI
BARANG LOGAM
Bolts & Nuts
Bolted joints are one of the most common elements in construction and machine design. They consist of cap screws or studs that capture and join other parts, and are secured with the mating of screw threads.
There are two main types of bolted joint designs. In one method the bolt is tightened to a calculated torque, producing a clamp load. The joint will be designed such that the clamp load is never overcome by the forces acting on the joint (and therefore the joined parts see no relative motion).
The other type of bolted joint does not have a designed clamp load but relies on the shear strength of the bolt shaft. This may include clevis linkages, joints that can move, and joints that rely on locking mechanism (like lock washers, thread adhesives, and lock nuts).
bacaan seterusnya KLIK SINI
Brass
Properties
The malleability and acoustic properties of brass have made it the metal of choice for brass musical instruments such as the trombone, tuba, trumpet, euphonium, and the French horn. Even though the saxophone is classified as a woodwind instrument and the harmonica is a free reed aerophone, both are also often made from brass. In organ pipes designed as "reed" pipes, brass strips are used as the "reeds".
Brass has higher malleability than copper or zinc. The relatively low melting point of brass (900 to 940°C, depending on composition) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.
bacaan seterusnya KLIK SINI
Brass & Brass Products (Zulraimin)
Eye Bolts & Nuts
Free Cutting Steel
Hammers (Muhammad Najmi)
Hand Hammers, hand hammer (Hasmie)
Hand Tools (Akmal)
Hardware (Muhd Syafik)
Iron (Namrod)
Iron & Iron Products (Nor Faseeha)
Metal & Metal Products (Nur Hafizah)
Parts & Supplies (NurLiyana)
Pliers (Nurafiqah)
Pneumatic Portable Screwdrivers (Nurnadiah)
Screwdrivers
Spanners
Steel (Siti Azilah)
Steel (muhammad syafiie)
Steel Products & Services (Sheldon)
Tools, Tools (Sylwyn)
Tools (Qubah Mohd)
Dari Wikipedia Bahasa Melayu, ensiklopedia bebas.
Lompat ke: navigasi, gelintar
Dalam bidang kimia, logam adalah sejenis unsur yang bersedia untuk membentuk ion (kation) dan mempunyai ikatan logam. Logam-logam biasanya diterangkan sebagai sebuah kekisi ion-ion positif (kation) yang dikelilingi awan-awan elektron tak setempat. Logam adalah satu daripada tiga kumpulan unsur yang dikenalpasti melalui sifat-sifat pengionan dan ikatan, yang lainnya adalah metaloid dan bukan logam. Di dalam jadual berkala, satu garis pepenjuru yang dilukir daripada boron (B) kepada polonium (Po) membezakan logam dan bukan logam. Unsur-unsur pada garis ini adalah metaloid, kadang kala dipanggil ala logam; unsur-unsur ke sebelah bawah kiri merupakan logam-logam, manakala sebelah atas kanan adalah bukan logam.
bacaan seterusnya KLIK SINI
BARANG LOGAM
Bolts & Nuts
Bolted joints are one of the most common elements in construction and machine design. They consist of cap screws or studs that capture and join other parts, and are secured with the mating of screw threads.
There are two main types of bolted joint designs. In one method the bolt is tightened to a calculated torque, producing a clamp load. The joint will be designed such that the clamp load is never overcome by the forces acting on the joint (and therefore the joined parts see no relative motion).
The other type of bolted joint does not have a designed clamp load but relies on the shear strength of the bolt shaft. This may include clevis linkages, joints that can move, and joints that rely on locking mechanism (like lock washers, thread adhesives, and lock nuts).
bacaan seterusnya KLIK SINI
Brass
Properties
The malleability and acoustic properties of brass have made it the metal of choice for brass musical instruments such as the trombone, tuba, trumpet, euphonium, and the French horn. Even though the saxophone is classified as a woodwind instrument and the harmonica is a free reed aerophone, both are also often made from brass. In organ pipes designed as "reed" pipes, brass strips are used as the "reeds".
Brass has higher malleability than copper or zinc. The relatively low melting point of brass (900 to 940°C, depending on composition) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.
bacaan seterusnya KLIK SINI
Brass & Brass Products (Zulraimin)
Eye Bolts & Nuts
Free Cutting Steel
Hammers (Muhammad Najmi)
Hand Hammers, hand hammer (Hasmie)
Hand Tools (Akmal)
Hardware (Muhd Syafik)
Iron (Namrod)
Iron & Iron Products (Nor Faseeha)
Metal & Metal Products (Nur Hafizah)
Parts & Supplies (NurLiyana)
Pliers (Nurafiqah)
Pneumatic Portable Screwdrivers (Nurnadiah)
Screwdrivers
Spanners
Steel (Siti Azilah)
Steel (muhammad syafiie)
Steel Products & Services (Sheldon)
Tools, Tools (Sylwyn)
Tools (Qubah Mohd)
Sunday, February 10, 2008
Monday, January 21, 2008
BAHAN KEJURUTERAAN - KAYU
KAYU
PENYIMPANAN KAYU
CHESAPEAKE WOODCRAFT
WOODWORK
STANDARD SIZE
Medium-density fibreboard
From Wikipedia, the free encyclopedia
Medium-density fiberboard output in 2005
Medium-density fiberboard (MDF or MDFB) is an engineered wood product formed by breaking down softwood into wood fibers, often in a defibrator, combining it with wax and resin, and forming panels by applying high temperature and pressure. It is a building material similar in application to plywood but made up of separated fibers, not wood veneers. It is denser than normal particle board.
Large-scale production of MDF began in the 1980s. Its name derives from the distinction in densities of fiberboard. MDF typically has a density of 600-800 kg/m³, in contrast to particle board (160-450 kg/m³) and to high-density fiberboard (600-1450 kg/m³). Similar manufacturing processes are used in making all types of fiberboard.
MDF is also known as Customwood or Craftwood.[citation needed].
MDF has been controversial in regard to its use of formaldehyde resins and the associated health risks. Thus, other resins are being considered and used instead of formaldehyde.
MDF is often used in school projects because of its flexibility.
A sample of MDF
Hollow extruded MDF decking boards, which appear to have the colouring/preservative in the manufacture
Contents[hide]
1 Manufacturing
2 Comparison to natural woods
3 Different kinds of MDF
4 References
5 External links
Manufacturing
MDF is a wood product created by breaking down a softwood into a powder, which is then mixed with wax and resin. The final finish is created by submitting the boards to high pressure and temperatures.
In Australia the main species of tree used for MDF is plantation-grown radiata pine. However a variety of other products have also been used including other woods, waste paper and fibers.
The trees are debarked after being cut. The bark can be sold for use in landscaping, or burned in on-site furnaces. The debarked logs are sent to the MDF plant where they go though the chipping process. A typical disk chipper contains 4-16 blades. Any resulting chips that are too large may be re-chipped; undersized chips may be used as fuel. All chips are then washed and checked for defects.
The chips are then compacted using a screwfeeder, and will be heated for 30-120 seconds to soften the wood; they are then fed into a defibrator which maintains high pressure and temperature. The pulp that exits from the defibrator is fine, fluffy, and light in weight and in colour.
From the defibrator the pulp enters a blow line where it is joined with wax (to improve moisture resistance) and resin (to stop the pulp from forming bundles). The material expands in size and is then heated by heating coils. When it comes out it may be stored in bins for an indefinite length of time.
After this drying period the board goes through a "Pendistor" process which creates 230-610 mm thick boards. Then it is cut and continues to the press. Here it is pressed for a few minutes, to make a stronger and denser board.
After pressing MDF is cooled in a star dryer, trimmed and sanded. In certain applications boards are also laminated for extra strength.
The Environmental Impact of MDF has greatly improved over the years. Today many MDF boards are made from a variety of materials. These include other woods, scrap, recycled paper, bamboo, carbon fibers and polymers, steel, glass, forest thinning and sawmill off-cuts.
Comparison to natural woods
Benefits of MDF:
Some varieties are less expensive than many natural woods
Isotropic (no grain), so no tendency to split
Consistent in strength and size
Flexible. Can be used for curved walls or surfaces.
Shapes well with a router.
Drawbacks of MDF:
Heavier (the resins are heavy)
Swells and breaks when waterlogged
Warps or expands if not sealed
Contains urea-formaldehyde which may cause eye and lung irritation when cutting and sanding
Dulls blades more quickly than many woods
Though it doesn't have a grain in the plane of the board, it does have one into the board. Screwing into the edge of a board will generally cause it to split in a fashion similar to delaminating.
Different kinds of MDF
There are different kinds of MDF, which are sometimes labeled by color:
Moisture-resistant is typically green
Fire-retardant MDF is typically red
High finition for powder lacking
Lighter densities of fiberboard are commonly marketed as ultralight or LDF boards.
References
External links
A video podcast from podcastschool.net
The Production Process of Humewood MDF (Humewood is a product of Hume Fiberboards Sdn Bhd, a Malaysian fiberboard manufacturer)
Wood Dust - dangers of exposure to wood dust, including MDF dust (from the Worker's Health Centre)
Medium Density Fiberboard - from Investment New Zealand, a division of New Zealand's economic development agency.
A personal experience of MDF toxicity
Retrieved from "http://en.wikipedia.org/wiki/Medium-density_fibreboard"
Categories: All articles with unsourced state
Mohd Zulraimin Zulkifli menyumbangkan bahan bacaan tambahan.
KLIK SINI untuk bacaan di window lain
Jenis kayu
Botanical Names: Hevea brasiliensisFamily
Name: Euphorbiaceae
Others Name: Rubbertree ( Malaysia ,Singapore ), para rubber , Arbol de caucho (Venezuela), Sibi-sibi (Guyana), Mapalapa (Surinam), Seringa, Seringueira (Brazil), Capi, Jeve, Shiringa (Peru). Jebe, Arbre De Para ( French), Parakautschukbaum, Cauchotero de Pará ,Siringa , Seringueira-branca, rapa (Fiji)
Working Properties:Obtained by tapping the trunks of the trees , good strength characteristic, easy machining and processing properties. Additionally, The wood is reported to saw without difficulty, planes easily to a smooth surface; tends to split in nailing. Therefore it can easily be stained and finished to meet various market requirements.
Durability: The wood is perishable and stains readily. Also highly susceptible to borer and termite attack as well as powder-post beetles.Wood Appearance: high color ( This wood is whitish yellow when freshly cut and seasons to cream, straw or light brown, often with a pinkish tinge.)
Rubberwood story:The rubber tree was originated came from Brazil named Hevea brasiliensis from the species family of Euphorbiaceae and widely planted for the production of latex in South East Asia country, mainly in Indonesia, Malaysia and Thailand.At the begining stage, rubber trees just for use in produce milky liquid known as latex that circulates through small tubes or veins for every 5- 7 years of growing. And these trees will discontinue for produce latex after 21 - 25 year, so at this moment, due to unproductive, therefore this trees are demand to fell (either replanting or other planning). Initially the felled trees were of low commercial value and mainly used as firewood, hence, due to worldwide technological developments & environment hazard, All these threes became valuable sources especially for furniture industrial. Today, Rubberwood becomes one of the most demanding and popular timbers for furniture maker (for both local & oversea market), therefore, this wood now can have categorised as environment-friendly due to hazard free to the environment and the supply is sustainable. In the sense that we are now using what was going as waste. Today Malaysia become one of the major resource and country who successful for supplying & exporting rubberwood ( for both sawn wood, raw, semi-finished, finished good and furniture accessories ) and for the production of panel products such as particleboards, woodfibre cement-bonded particleboards ,fibreboards (MDF),, plywood and other products for both local and oversea market demand.
Perabut Seong Aik (or known as PSA ) is one of the manufacturer who leading to produce rubber wood furniture. click here for product view
Kayu dalam pasaran
Papan buatan
PENYIMPANAN KAYU
CHESAPEAKE WOODCRAFT
WOODWORK
STANDARD SIZE
Medium-density fibreboard
From Wikipedia, the free encyclopedia
Medium-density fiberboard output in 2005
Medium-density fiberboard (MDF or MDFB) is an engineered wood product formed by breaking down softwood into wood fibers, often in a defibrator, combining it with wax and resin, and forming panels by applying high temperature and pressure. It is a building material similar in application to plywood but made up of separated fibers, not wood veneers. It is denser than normal particle board.
Large-scale production of MDF began in the 1980s. Its name derives from the distinction in densities of fiberboard. MDF typically has a density of 600-800 kg/m³, in contrast to particle board (160-450 kg/m³) and to high-density fiberboard (600-1450 kg/m³). Similar manufacturing processes are used in making all types of fiberboard.
MDF is also known as Customwood or Craftwood.[citation needed].
MDF has been controversial in regard to its use of formaldehyde resins and the associated health risks. Thus, other resins are being considered and used instead of formaldehyde.
MDF is often used in school projects because of its flexibility.
A sample of MDF
Hollow extruded MDF decking boards, which appear to have the colouring/preservative in the manufacture
Contents[hide]
1 Manufacturing
2 Comparison to natural woods
3 Different kinds of MDF
4 References
5 External links
Manufacturing
MDF is a wood product created by breaking down a softwood into a powder, which is then mixed with wax and resin. The final finish is created by submitting the boards to high pressure and temperatures.
In Australia the main species of tree used for MDF is plantation-grown radiata pine. However a variety of other products have also been used including other woods, waste paper and fibers.
The trees are debarked after being cut. The bark can be sold for use in landscaping, or burned in on-site furnaces. The debarked logs are sent to the MDF plant where they go though the chipping process. A typical disk chipper contains 4-16 blades. Any resulting chips that are too large may be re-chipped; undersized chips may be used as fuel. All chips are then washed and checked for defects.
The chips are then compacted using a screwfeeder, and will be heated for 30-120 seconds to soften the wood; they are then fed into a defibrator which maintains high pressure and temperature. The pulp that exits from the defibrator is fine, fluffy, and light in weight and in colour.
From the defibrator the pulp enters a blow line where it is joined with wax (to improve moisture resistance) and resin (to stop the pulp from forming bundles). The material expands in size and is then heated by heating coils. When it comes out it may be stored in bins for an indefinite length of time.
After this drying period the board goes through a "Pendistor" process which creates 230-610 mm thick boards. Then it is cut and continues to the press. Here it is pressed for a few minutes, to make a stronger and denser board.
After pressing MDF is cooled in a star dryer, trimmed and sanded. In certain applications boards are also laminated for extra strength.
The Environmental Impact of MDF has greatly improved over the years. Today many MDF boards are made from a variety of materials. These include other woods, scrap, recycled paper, bamboo, carbon fibers and polymers, steel, glass, forest thinning and sawmill off-cuts.
Comparison to natural woods
Benefits of MDF:
Some varieties are less expensive than many natural woods
Isotropic (no grain), so no tendency to split
Consistent in strength and size
Flexible. Can be used for curved walls or surfaces.
Shapes well with a router.
Drawbacks of MDF:
Heavier (the resins are heavy)
Swells and breaks when waterlogged
Warps or expands if not sealed
Contains urea-formaldehyde which may cause eye and lung irritation when cutting and sanding
Dulls blades more quickly than many woods
Though it doesn't have a grain in the plane of the board, it does have one into the board. Screwing into the edge of a board will generally cause it to split in a fashion similar to delaminating.
Different kinds of MDF
There are different kinds of MDF, which are sometimes labeled by color:
Moisture-resistant is typically green
Fire-retardant MDF is typically red
High finition for powder lacking
Lighter densities of fiberboard are commonly marketed as ultralight or LDF boards.
References
External links
A video podcast from podcastschool.net
The Production Process of Humewood MDF (Humewood is a product of Hume Fiberboards Sdn Bhd, a Malaysian fiberboard manufacturer)
Wood Dust - dangers of exposure to wood dust, including MDF dust (from the Worker's Health Centre)
Medium Density Fiberboard - from Investment New Zealand, a division of New Zealand's economic development agency.
A personal experience of MDF toxicity
Retrieved from "http://en.wikipedia.org/wiki/Medium-density_fibreboard"
Categories: All articles with unsourced state
Mohd Zulraimin Zulkifli menyumbangkan bahan bacaan tambahan.
KLIK SINI untuk bacaan di window lain
Jenis kayu
Botanical Names: Hevea brasiliensisFamily
Name: Euphorbiaceae
Others Name: Rubbertree ( Malaysia ,Singapore ), para rubber , Arbol de caucho (Venezuela), Sibi-sibi (Guyana), Mapalapa (Surinam), Seringa, Seringueira (Brazil), Capi, Jeve, Shiringa (Peru). Jebe, Arbre De Para ( French), Parakautschukbaum, Cauchotero de Pará ,Siringa , Seringueira-branca, rapa (Fiji)
Working Properties:Obtained by tapping the trunks of the trees , good strength characteristic, easy machining and processing properties. Additionally, The wood is reported to saw without difficulty, planes easily to a smooth surface; tends to split in nailing. Therefore it can easily be stained and finished to meet various market requirements.
Durability: The wood is perishable and stains readily. Also highly susceptible to borer and termite attack as well as powder-post beetles.Wood Appearance: high color ( This wood is whitish yellow when freshly cut and seasons to cream, straw or light brown, often with a pinkish tinge.)
Rubberwood story:The rubber tree was originated came from Brazil named Hevea brasiliensis from the species family of Euphorbiaceae and widely planted for the production of latex in South East Asia country, mainly in Indonesia, Malaysia and Thailand.At the begining stage, rubber trees just for use in produce milky liquid known as latex that circulates through small tubes or veins for every 5- 7 years of growing. And these trees will discontinue for produce latex after 21 - 25 year, so at this moment, due to unproductive, therefore this trees are demand to fell (either replanting or other planning). Initially the felled trees were of low commercial value and mainly used as firewood, hence, due to worldwide technological developments & environment hazard, All these threes became valuable sources especially for furniture industrial. Today, Rubberwood becomes one of the most demanding and popular timbers for furniture maker (for both local & oversea market), therefore, this wood now can have categorised as environment-friendly due to hazard free to the environment and the supply is sustainable. In the sense that we are now using what was going as waste. Today Malaysia become one of the major resource and country who successful for supplying & exporting rubberwood ( for both sawn wood, raw, semi-finished, finished good and furniture accessories ) and for the production of panel products such as particleboards, woodfibre cement-bonded particleboards ,fibreboards (MDF),, plywood and other products for both local and oversea market demand.
Perabut Seong Aik (or known as PSA ) is one of the manufacturer who leading to produce rubber wood furniture. click here for product view
Kayu dalam pasaran
Papan buatan
Sunday, January 13, 2008
MESIN
MESIN
1. Mesin ialah sejenis alat yang boleh bergerak atau digerakkan apabila dikenakan kuasa.
2. Kuasa tersebut terdiri daripada 3 jenis iaitu Pneumatik, Hidraulik dan Elektrik.
3. Mesin ialah istilah sains bagi apa-apa peranti atau perkakas yang menghasilkan tenaga
(sumbangan Nurnadiah Kamaruddin & rakan-rakan)
Terdapat beberapa jenis mesin yang digunakan di dalam bengkel. Antaranya:
- mesin yang menggunakan kuasa elektrik
- mesin yang menggunakan kuasa hidraulik
- mesin yang menggunakan kuasa pneumatik
Bending Rollers / Plate Bending Machines
Three Roll Pinch Pyramid Plate Bending Machines
- The machine incorporates a fixed top roll & two independently adjustable bottom rolls.
- Both edges of the plate can be pre-bent with a single insertion of the plate.
- Pre-Pinching and Bending are done by clamping the plate between top roll and one bottom roll
and bending the clamped portion by another bottom roll to the desired radius by rolling.
The same operation is then repeated using the top roll and the opposite bottom roll to pre-
pinch the other end of the plate.
- After pre-bending of edges is done, both the bottom rolls are leveled and the plate bending
operation is resumed to bend the plate to the desired radius or cylinder.
Hand Operated Bending Rollers - Slip Type
- Cast Iron frame reinforced by tie rods for machines having roll diameter of 25 & 50 mm
- Steel Body frame for machines having roll diameter of 64 & 76 mm
- Roll Slip Out arrangement for withdrawal of fully formed cylinders without deformation
Motorized Light Duty Bending Rollers
- Steel Body frame
- Steel Gears
- Roll Slip Out arrangement for withdrawal of fully formed cylinders without deformation
Motorized Heavy Duty Bending Rollers
- All steel fabrication housing
- Rolls of forged steel moving in Gun Metal bushes
- Drive through steel gears and reduction gear box
- Horizontal grooves provided on bottom rolls
Taper Bending Rollers
Knife Sharpening / Blade Grinding Machines
Features:
- Most suitable for grinding knifes and blades of paper cutting machines, metal cutting shears, etc.
- Electro-Magnetic Clutch / 360o Swiveling Table for flat, bevel and multi surface grinding
Standard Accessories: Motors, panel board, electro-magnetic chuck, one set of grinding segments fitted on the machine, coolant pump, water tank, tools, etc.
1. Machine Bed
2. Guideway
3. Machine Table
4. Grinding Head Carriage
5. Down-Feed for Grinding Tool
6. Grinding Motor
7. Grinding Head
8. Cooling System
9. Electrical unit
Hand Lever Shearing Machines
Light Duty Machine
Light Duty Geared Machine
Geared Machine with Angle & Tee Cutting Attachments
Heavy Duty Geared Machine
Rod Cutting Machine
Punching Machine
Combined Punching & Shearing Machines
Metal Cutting Hydraulic Hacksaw & Bandsaw
Hydraulic Hacksaw
- ‘V’ belt drive with two speeds by step pulley
- Hydraulic relief to saw blade on non-cutting stroke
- Automatic lifting of saw blade after cutting action
Hydraulic Horizontal Metal Cutting Bandsaw
- Smooth cutting achieved by hydraulically controlled feed
- Worm Gear Drive
- Motor stops automatically on finishing the cut
1. Mesin ialah sejenis alat yang boleh bergerak atau digerakkan apabila dikenakan kuasa.
2. Kuasa tersebut terdiri daripada 3 jenis iaitu Pneumatik, Hidraulik dan Elektrik.
3. Mesin ialah istilah sains bagi apa-apa peranti atau perkakas yang menghasilkan tenaga
(sumbangan Nurnadiah Kamaruddin & rakan-rakan)
Terdapat beberapa jenis mesin yang digunakan di dalam bengkel. Antaranya:
- mesin yang menggunakan kuasa elektrik
- mesin yang menggunakan kuasa hidraulik
- mesin yang menggunakan kuasa pneumatik
Bending Rollers / Plate Bending Machines
Three Roll Pinch Pyramid Plate Bending Machines
- The machine incorporates a fixed top roll & two independently adjustable bottom rolls.
- Both edges of the plate can be pre-bent with a single insertion of the plate.
- Pre-Pinching and Bending are done by clamping the plate between top roll and one bottom roll
and bending the clamped portion by another bottom roll to the desired radius by rolling.
The same operation is then repeated using the top roll and the opposite bottom roll to pre-
pinch the other end of the plate.
- After pre-bending of edges is done, both the bottom rolls are leveled and the plate bending
operation is resumed to bend the plate to the desired radius or cylinder.
Hand Operated Bending Rollers - Slip Type
- Cast Iron frame reinforced by tie rods for machines having roll diameter of 25 & 50 mm
- Steel Body frame for machines having roll diameter of 64 & 76 mm
- Roll Slip Out arrangement for withdrawal of fully formed cylinders without deformation
Motorized Light Duty Bending Rollers
- Steel Body frame
- Steel Gears
- Roll Slip Out arrangement for withdrawal of fully formed cylinders without deformation
Motorized Heavy Duty Bending Rollers
- All steel fabrication housing
- Rolls of forged steel moving in Gun Metal bushes
- Drive through steel gears and reduction gear box
- Horizontal grooves provided on bottom rolls
Taper Bending Rollers
Knife Sharpening / Blade Grinding Machines
Features:
- Most suitable for grinding knifes and blades of paper cutting machines, metal cutting shears, etc.
- Electro-Magnetic Clutch / 360o Swiveling Table for flat, bevel and multi surface grinding
Standard Accessories: Motors, panel board, electro-magnetic chuck, one set of grinding segments fitted on the machine, coolant pump, water tank, tools, etc.
1. Machine Bed
2. Guideway
3. Machine Table
4. Grinding Head Carriage
5. Down-Feed for Grinding Tool
6. Grinding Motor
7. Grinding Head
8. Cooling System
9. Electrical unit
Hand Lever Shearing Machines
Light Duty Machine
Light Duty Geared Machine
Geared Machine with Angle & Tee Cutting Attachments
Heavy Duty Geared Machine
Rod Cutting Machine
Punching Machine
Combined Punching & Shearing Machines
Metal Cutting Hydraulic Hacksaw & Bandsaw
Hydraulic Hacksaw
- ‘V’ belt drive with two speeds by step pulley
- Hydraulic relief to saw blade on non-cutting stroke
- Automatic lifting of saw blade after cutting action
Hydraulic Horizontal Metal Cutting Bandsaw
- Smooth cutting achieved by hydraulically controlled feed
- Worm Gear Drive
- Motor stops automatically on finishing the cut
ALATAN TANGAN
ALAT TANGAN
Alatan tangan dibahagikan kepada beberapa bahagian mengikut fungsi dan kegunaannya. Antaranya:
- alat menanda
- alat memotong
- alat membentuk
- alat memasang dan
- alat menguji.
TAJUK : PERALATAN TANGAN ASAS ( COMMON HAND TOOLS)
TUJUAN: Kertas penerangan ini akan menerangkan kegunaan Spana, screw driver dan playar ,jenis-jenis spana, screw driver dan playar.
PENERANGAN:
Alat-alat tangan asas amatlah penting dalam sistem Penyejukbekuan dan Penyamanan Udara di mana alat-alat ini diperlukan ketika kerja-kerja penyeleggaraan, dan membaikpulih ke atas unit-unit tersebut.
SEPANA
Digunakan untuk mengetat atau melonggarkan nat atau skru
Jenis-jenis sepana
Terdapat beberapa jenis sepana yang biasa digunakan dalam bengkel kejuruteraan ialah:-
- Sepana soket ( socket spanner),Sepana kekotak (spanner box)
- Sepana hujung terbuka (open spanner),Sepana gabungan (comman spanner)
- Sepana hidup (adjustable),Sepana nat kembang
- Sepana paip,Sepana injap servis,Sepana daya kilas,Kunci allen,Sepana set skru
a) SEPANA SOKET
Sepana ini begitu meluas digunakan, terutamanya untuk membuka, mengetat atau melonggarkan nat yang kepalanya mempunyai segi. Sepana jenis ini digunakan pada tempat yang sempit dan tempat yang bersudut.
b) Sepana kekotak
Sepana jenis ini hampir serupa dengan sepana socket, tetapi bahagian dalamnya berbentuk kekotak.
c) Sepana paip
Digunakan untuk mengetat atau melonggarkan penyambung-penyambung paip dalam kerja-kerja pemaipan.
d) Sepana injap servis
Digunakan untuk melaraskan injap servis pada kedudukan hadapan, pertengahan dan belakang pada pemampat.
e) Sepana daya kilas
Digunakan untuk menyukat kekuatan piuh apabila mengetatkan nat
f) Kunci allen
Digunakan bagi mengetat dan melolnggarkan skru allen segienam atau segiempat di bahagian kepalanya
g) Sepana set skru
Digunakan untuk mengetat atau menlonggarkan skru yang berbentuk heksagon, philip dan rata
h) Sepana hujung terbuka
Kebiasaannya digunakan pada tempat yang terbuka
i) Sepana gabungan atau paduan
Adalah gabungan antara sepana hujung terbuka dengan sepana gelang (ring spana)
j) Sepana hidup (adjustable)
Ia boleh dilaraskan mengikut saiz nat dengan memutarkan skru pelaras yang terdapat pada badannya
k) Sepana nat kembang
Digunakan khusus dalam sistem pemaipan tiub kuprum bagi mengetat dan melonggarkan nat kembang.
1. Pemutar skru.
Digunakan untuk mengetat atau melonggarkan skru yang kepalanya berbentuk
a) Pemutar skru phillip
b) Pemutar skru rata
c) Pemutar skru kekotak
3) Playar
Digunaka untuk mengepit atau memegang sesuatu bendakerja seperti dalam kerja-kerja mengimpal.
Jenis-jenis Playar
a) Playar pepenjuru
Digunakan untuk memotong dawai dan penjuru-penjuru kepingan logam yang nipis.
b) Playar Muncung Tirus
Playar jenis ini digunakan bagi mengapit nat atau skru pada tempat yang sempit. Playar ini juga boleh digunakan untuk memotong dawai.
c) Playar pengapit
Digunakan untuk mengapit tiub kupram selepas proses mengecas dijalankan.
d) Playar tukang talian
Digunakan untuk memotong kabel atau dawai elektrik dalam kerja-kerja pendawaian. Getah pada bahagian pemegang bertindak sebagai penebat untuk keselamatan tukang talian
e) Playar penyambung gelincir
Digunakan untuk mengapit bahan atau logam yang tebal dan juga untuk nat.
f) Playar pengapit ragum
Digunakan untuk memegang bendakerja secara mengapit bagi kerja-kerja mengimpal, mencanai atau mengerudi.
g) Playar paduan
Digunakan bagi mengapit bendakerja yang halus, nipis dan juga untuk membengkok atau melengkongkan dawai.
h) Playar pencengkam
Digunakan untuk mencengkam bendakerja semasa kerja-kerja mengimpal, mencanai atau menggerudi.
(sumbangan siti fasliyana)
* gambar tidak dapat dipaparkan atas gangguan teknikal
Alatan tangan dibahagikan kepada beberapa bahagian mengikut fungsi dan kegunaannya. Antaranya:
- alat menanda
- alat memotong
- alat membentuk
- alat memasang dan
- alat menguji.
TAJUK : PERALATAN TANGAN ASAS ( COMMON HAND TOOLS)
TUJUAN: Kertas penerangan ini akan menerangkan kegunaan Spana, screw driver dan playar ,jenis-jenis spana, screw driver dan playar.
PENERANGAN:
Alat-alat tangan asas amatlah penting dalam sistem Penyejukbekuan dan Penyamanan Udara di mana alat-alat ini diperlukan ketika kerja-kerja penyeleggaraan, dan membaikpulih ke atas unit-unit tersebut.
SEPANA
Digunakan untuk mengetat atau melonggarkan nat atau skru
Jenis-jenis sepana
Terdapat beberapa jenis sepana yang biasa digunakan dalam bengkel kejuruteraan ialah:-
- Sepana soket ( socket spanner),Sepana kekotak (spanner box)
- Sepana hujung terbuka (open spanner),Sepana gabungan (comman spanner)
- Sepana hidup (adjustable),Sepana nat kembang
- Sepana paip,Sepana injap servis,Sepana daya kilas,Kunci allen,Sepana set skru
a) SEPANA SOKET
Sepana ini begitu meluas digunakan, terutamanya untuk membuka, mengetat atau melonggarkan nat yang kepalanya mempunyai segi. Sepana jenis ini digunakan pada tempat yang sempit dan tempat yang bersudut.
b) Sepana kekotak
Sepana jenis ini hampir serupa dengan sepana socket, tetapi bahagian dalamnya berbentuk kekotak.
c) Sepana paip
Digunakan untuk mengetat atau melonggarkan penyambung-penyambung paip dalam kerja-kerja pemaipan.
d) Sepana injap servis
Digunakan untuk melaraskan injap servis pada kedudukan hadapan, pertengahan dan belakang pada pemampat.
e) Sepana daya kilas
Digunakan untuk menyukat kekuatan piuh apabila mengetatkan nat
f) Kunci allen
Digunakan bagi mengetat dan melolnggarkan skru allen segienam atau segiempat di bahagian kepalanya
g) Sepana set skru
Digunakan untuk mengetat atau menlonggarkan skru yang berbentuk heksagon, philip dan rata
h) Sepana hujung terbuka
Kebiasaannya digunakan pada tempat yang terbuka
i) Sepana gabungan atau paduan
Adalah gabungan antara sepana hujung terbuka dengan sepana gelang (ring spana)
j) Sepana hidup (adjustable)
Ia boleh dilaraskan mengikut saiz nat dengan memutarkan skru pelaras yang terdapat pada badannya
k) Sepana nat kembang
Digunakan khusus dalam sistem pemaipan tiub kuprum bagi mengetat dan melonggarkan nat kembang.
1. Pemutar skru.
Digunakan untuk mengetat atau melonggarkan skru yang kepalanya berbentuk
a) Pemutar skru phillip
b) Pemutar skru rata
c) Pemutar skru kekotak
3) Playar
Digunaka untuk mengepit atau memegang sesuatu bendakerja seperti dalam kerja-kerja mengimpal.
Jenis-jenis Playar
a) Playar pepenjuru
Digunakan untuk memotong dawai dan penjuru-penjuru kepingan logam yang nipis.
b) Playar Muncung Tirus
Playar jenis ini digunakan bagi mengapit nat atau skru pada tempat yang sempit. Playar ini juga boleh digunakan untuk memotong dawai.
c) Playar pengapit
Digunakan untuk mengapit tiub kupram selepas proses mengecas dijalankan.
d) Playar tukang talian
Digunakan untuk memotong kabel atau dawai elektrik dalam kerja-kerja pendawaian. Getah pada bahagian pemegang bertindak sebagai penebat untuk keselamatan tukang talian
e) Playar penyambung gelincir
Digunakan untuk mengapit bahan atau logam yang tebal dan juga untuk nat.
f) Playar pengapit ragum
Digunakan untuk memegang bendakerja secara mengapit bagi kerja-kerja mengimpal, mencanai atau mengerudi.
g) Playar paduan
Digunakan bagi mengapit bendakerja yang halus, nipis dan juga untuk membengkok atau melengkongkan dawai.
h) Playar pencengkam
Digunakan untuk mencengkam bendakerja semasa kerja-kerja mengimpal, mencanai atau menggerudi.
(sumbangan siti fasliyana)
* gambar tidak dapat dipaparkan atas gangguan teknikal
http://spanar3292.tripod.com/alatan%20_tangan.htm
(sumbangan nur affini)
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