Pengenalan jenis kayu
• Indonesia memiliki kurang lebih 4.000 jenis kayu
• Jenis kayu komersial penting sekitar 400 jenis
• Diperlukan teknik pengenalan jenis kayu untuk memberi kepastian dalam perdagangan kayu
• Perlindungan jenis: menghindari ilegal trading, penyelundupan, dll. WOOD IDENTIFICATION KEYS
A collection of labeled wood samples can be invaluable in helping you b ecome familiar with a variety of woods. It may also contain a species
you wish to identify.
I orrectly identifying an unfamiliar
\; wood sample out of thousands of possibilities requires close observation, and a thorough knowledge ofwood and its properties. But as a practical matter, the possible choices are usuallylimited to several familiar species, and a commer- cially available set of labeled wood sam- ples, such as the one shown at right, may include a piece that matches the wood you are attempting to identifr. Most often, however, you will need to record the features of a sample, then use a wood identification key from a book to make sense ofyour results.
An identification key is essentially a master list of woods and their proper- ties that serves as a cross-reference to link the features of a particular sample to a species name. Some keys require that you compare their entries against features that are visible to the naked eye or with a 10x magnifier, while others demand that you note microscopic details. Still other keys are based on the user having wide-ranging sensory infor- mation about the wood, including its colot odor and texture, and the bark and leaf shape of the tree from which it came.
Using a key is like climbing the branches of a tree. You are asked to answer a series of paired statements, choosing the one that best describes the wood in question and proceeding to the next pair indicated. At each statement, the user forks onto a different branch
until reaching a leaf that identifies the sample. The first statement may involve the texture of the wood. If the wood is porous, for example, you are sent to one set of statements; if it is non-porous, you jump to a different set of statements. You continue this way, flipping from page to page in a book, as each answer gradual- lyreduces the choices. Finally, the search is narrowed to a single species.
Avoid keys that try to cover every wood species in the world; they will prove too general. Choose one that describes trees in a specific region, such as North American softwoods or tropical hard- woods. Several classic keys can be found in woodworking boola; check your local library or boolstore. Some public agen-
cies (below) also offer wood identifica- tion services.
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SOURCES FOR WOOD IDEI{TIFICATIOI{
Books
Edlin, Herbert L., What Wood ls That?
A Manual of Wood ldentification.
New York: Viking, 1969.
Hoadley, Bruce, ldentifying Wood.
Nevvton, Connecticut: Tau nton Press, 1990.
Panshin, A.J. and DeZeeuw, Carl,Textbook of Wood Technologr.
New York: McGraw Hill, 1980.
Rendfe, 8.J., World Timbers: Volumes 1-3. London: Ernest Benn, 1970.
Sharp, John 8., Wood ldentification:
A Manual for The Non-Profexional.
Knoxville: University of Tennessee
Agricultural Extension Service, Forestry and Wildlife Extension, 1990.
Timber Research Development Association, Timbers of the World:
Volumes I and 2. Lancaster;
Construction Press, 1979.
Agencies that offer wood identification services
Center For Wood Anatomy Research U.S. Forest Products Laboratory 1 Gifford Pinchot Drive
Madison, Wisconsi n 53705-2398 International Wood Collectors Societv 2913 Third Street
Trenton, Michigan 48183
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Pengenalan jenis kayu (2)
• Cara makroskopis non strukturil yang sering disebut juga
sebagai “ciri umum”: warna, kilap, kesan raba, bau dan rasa &
reaksi kimia.
• Cara makroskopis strukturil: lingkaran tumbuh, kayu gubal
dan teras, jari-jari kayu, pori, parenkim & saluran damar atau
getah
Pengenalan jenis kayu (3)
Pengenalan secara mikroskopis dilakukan bila cara makroskopis masih meragukan. Ciri mikroskopis: pori kayu, ukuran pori, susunan dan bentuk pori, saluran interseluler, serat (pada kayu keras) atau trakeid (pada kayu lunak), jari-jari kayu, parenkim & tilosis
Pita tangensial Diagonal Dendritik
Susunan Pori Kayu
Struktur anatomi kayu menyerupai seperti “finger- print” dalam pengenalan jenis kayu
Sifat-Sifat Dasar Kayu
• Sifat fisika
• Sifat kimia
• Sifat mekanik
Sifat Fisik: Kadar Air Kayu
• Air merupakan penyusun alami dari semua bagian pohon hidup.
• Pohon yang baru ditebang memiliki kadar air yang tinggi antara 40 – 200%
• Kayu dalam penggunaan kadar airnya menyesuaikan dengan lingkungan sekitarnya berkisar antara 12-16%.
• Kadar air kayu adalah jumlah air pada sepotong kayu yang
dinyatakan sebagai persentase terhadap berat kayu pada kondisi tanpa air (kering tanur/BKT).
Sifat Fisik: Berat Jenis Kayu
• Perbandingan dari kerapatan suatu bahan terhadap
kerapatan bahan standard yang ditentukan pada suhu tertentu.
• Air pada kerapatannya yang tertinggi (4oC; 39.2oF)
merupakan bahan standard yang universal untuk penen tuan BJ semua bahan --->
kerapatannya = 1 g/cm3; 1000 kg/m3; 62,4 pon/kaki3
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UNDERSTANDING WOOD
Specific grnvity is a better irdicator of n wood's weight thart size. With a speciJic gravity of 0.90, a piece of cborry weiglrs the sanrc tts a trtttclt lnrger block of white pine, wlrcse speciJic grovity is only 0.35.
TYPES ()F GRAIN
Featured tn lumber wiLh even wood ftbere thaL are parallel Lo the verLtcal axta of the trunk; makea for eLronq wood, but hae ltttle or no fi4ure
Found tn lumber where the ftbera devi' aLe from the verLtcal axie of the Lrunk;
not ao atronq ae etraiqhL-qratned wood, but producee an attracttve fiqure
treea with twtEt ed trunka; common in 1coLch pine and aweet cheetnuL
Interlocked grain
Found tn lumber from treeE with oppoein7 internal LwtaLe;
eomeLimee found in elm and very common in tropical epeciee Froduced by wood ftbere Lhat undulate tn ehort, even wavee: yielde fiddleback ftqure
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Kayu dengan Berat Jenis Yang Berbeda
• Mekanika kayu berhubungan dengan sifat yang
membicarakan aksi gaya-gaya luar pada kayu dan reaksinya
• Ada 3 macam gaya primer yang dapat beraksi pada kayu : 1. Gaya dapat berupa aksi penekanan/compression bila
gaya-gaya tersebut memperkecil
dimensi/mengurangi volume bendanya; disebut
“stress tekan/compressive stress”
2. Jika gayanya cenderung menambah
dimensi/volumenya maka gaya yang terjadi adalah tarikan/tensile; disebut “stress tensile/stres tarik”
3. Gaya dengan arah berlawanan yang memberikan aksi memisahkan benda kayu menjadi 2 bagian; disebut “
“stress geser/shear stress”
Sifat Mekanika kayu
Gaya tarik (Tensile)
Gaya tekan (Compressive) Gaya geser (Shearing)
Reaksi pada kayu àKekuatan tekan
(Compresive strength)
àKekuatan tarik (Tensile strength) àKekuatan geser
(Shear strength)
Pemanfaatan Kayu Untuk Tujuan
Struktural Bangunan
Sifat Kimia: Komposisi Organik Kayu
Penyusun elemen dalam kayu berkombinasi menjadi sejumlah polimer organik, yaitu selulosa, hemiselulosa dan lignin. Sifat ini penting untuk pemanfaatan kayu untuk produk kertas, bioenergi, produk kimia, dsb.
Jenis Selulosa Hemiselulosa Lignin
(% berat kering)
Kayukeras (hardwood) 40 – 44 15 – 35 18 – 25
Kayulunak (softwood) 40 – 44 20 – 32 25 – 35
Serat Akasia Serat pada kertas Produk kertas
Pengolahan Hasil Hutan
Tomy listyanto
Suatu usaha merubah kayu bulat (log) menjadi papan/balok kayu persegi pada sisi-sisinya dan pemotongan untuk mendapatkan dimensi panjang sebagai bahan baku untuk pengolahan lebih lanjut.
(Haygreen & Bowyer, 1996)
Pengolahan Primer Kayu Solid
Penggergajian Kayu
Perbedaan Sortimen Kayu Gergajian
Flatsawn
Quatersawn
Pengolahan Primer Kayu Solid
Penggunaan Kayu Solid – Kayu Komposit
Kayu gergajian solid
Kayu laminasi Laminasi dengan
perekatan
Dimensi lebar
Dimensi panjang Partikel kayu Finir kayu
Kayu lapis (Plywood) Papan partikel (Particleboard)
Pengolahan Finir Kayu & Kayu Lapis
Pengolahan Primer Komposit Kayu
FROM LOG TO VENE,ER
1'\ nce its bark is stripped away, a log
\J .un be cut into veneer in one oi three rvays: saw cutting, rotary cutting or flat slicing. Saw cutting, which goes back to the early 19th Centi"rry, employs huge circular saws to rip strips of veneer from logs. Although not as efficient as other techniques, saw cutting is still used to produce some crotch veneers from irregularly grained or dense woods such as ebony.
Rotary cutting and flat slicing can produce veneers as thin as 7s to l,/r zo inch and as long as I B feet. In rotary cutting, a log mounted in a huge lathe rotates against a presslu€ bar while a razor-sharp knife oeels off a continuous sheet of veneeithe length of the log. Fir plp,vood, as well as some decorative veneers such as bird's-eye maple, are normally rotary cut. Half-round, rift and back cutting are variations that produce veneer from half-loss rather than whole ones.
In flat slicing, a half-log is held onto a frame that swings r-rp and down against a stationary horizontai knife; a slice of veneer is removed with every down- stroke. FIat slicing produces crown-cut veneers. A type of flat slicing known as quarter-clrt slicing is used on woods that display a striking figure when quarter- sawn, as in sapeie, white oak or lacewood.
Flat-sliced sheets of verteer move nlortg tt conveyor for drying tud
storage hr n vetreer .fnctory.
VENEER-CUTTING METH(lDS
Rotary autting Used Lo cut con' etruction plywood and eome decora' tive veneera guch ao btrd'o-eye maple
Half-round autting A method used for burla and aome decorattve apectea
Eack cutting A rotary cutting method that. yielde buLL and croLch veneer9
Flat eliaing Uaed to make crown- cut veneer?; pro' ducea veneera wiLh repeatinq figure thaL facrltLaf,ea book' matching and oLher decorative effects
Quarber-aui aliaing Uaed to cut decora- f,tve veneerg, auch ae ribbon, atripe and flake, that are obtarned from quar' Lereawn loqe
Ri{t cutting Yielde veneer wtth the raye at rou7hly 45" to the eurface;
uoed primarily on whiLe oak
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• Perumahan dan konstruksi serta industri membutuhkan produk panel yang berdimensi lebar sehingga mendorong berkembangnya teknologi komposit kayu (kayu lapis, papan partikel, papan serat dsb).
• Finir: lembaran papan tipis dengan tebal seragam, yang diperoleh melalui : pengupasan, pengirisan, dan penggergajian
Kayu lapis merupakan komposit kayu yang dibuat dengan menggabungkan beberapa lembar finir kayu yang umumnya berjumlah ganjil yang disusun bersilangan dengan menggunakan perekat.
Penggunaan Kayu Lapis
Pengolahan Primer Komposit Kayu
Pengolahan Papan Partikel
Pengolahan Primer Komposit Kayu
Pengolahan Papan Partikel
• Papan partikel adalah produk panil yang dihasilkan dengan memampatkan partikel-partikel kayu dan sekaligus mengikatnya dengan suatu perekat (Haygreen dan Bowyer, 1996).
• Papan partikel merupakan salah satu produk papan tiruan yang memanfaatkan limbah kayu, potongan-potongan kecil kayu (ketaman, serutan, partikel, serpihan) kemudian dicampur perekat hingga merata, selanjutnya dilakukan pengempaan pendahuluan dan pengempaan panas.