Today, many types of wood are used in the back of commercial trucks, and it is used in a variety of forms: from sections for a frame, chipboard for partitions to cladding plywood for decorative panels. Manufactured wood panels are also used in combination with other materials, such as aluminum and plastics, for the production of special-purpose panels, which include heat and sound insulation and improve resistance to general wear and weather.
Some lumber is more suitable for car bodies than others because of their superior strength, durability, decomposition and fire or appearance.
Although wood is used in many forms, they are all derived from either softwood or moderate or tropical hardwood.
Conifer.
There are a large number of coniferous trees, which include many varieties of pine, fur and spruce, which make up about 90 percent of all tree species used mainly in the United States and Europe. These trees are commonly found in the northern hemisphere; most of them are cone-shaped and evergreen, but there are some exceptions. In fact, some types of conifer are harder than hardwood.
There is a good supply of softwood, and since it takes less time to mature, and they work easier, they are usually cheaper than hardwood. Softwoods are used for sides and floors of vehicles with mineral carriers, as they are cheaper and easier to replace. It is also used for manufactured panels for other commercial vehicles.
Wood
They are derived from broad leafy trees, and there are more than 2000 varieties, including such well-known types as oak, ash, teak and mahogany. All basal wood, which is much softer than soft wood, is in fact hardwood, since it is the structure that decides the non-texture group.
Since hardwoods take much longer to mature, they are harder to get and work, and much longer, they are much more expensive. However, they are usually much stronger, more durable and have much more applications than conifers.
Hardwoods are divided into two groups:
1. Tropical. These are trees found in Central Africa, India and South America, and include many different types of teak, mahogany and ebony.
2. Died The varieties found in this group are oak, walnut and ash - some of the moderate hardwoods found in the USA, Europe, Japan and Australia.
Hardwood is used for veneering and in some types of veneer on panels for interior decoration. Also hardwood, such as ash, is very suitable for curved frame elements.
Manufactured panels.
Plywood, block board, chipboard, MDF and fibreboard panels are often used instead of solid wood panels and have many advantages. They can be produced in large sizes, often stronger and more stable, which means that labor costs can be reduced compared with other methods of covering large areas with equivalent sheet pile and groove sheet wood.
Plywood.
Plywood is made by gluing veneer layers together at a right angle to each other. This leads to splitting and significantly increases the strength of the panel. Curved elements can also be made by laying veneers on a suitable shape or shape before gluing.
Birch, ash, pine and fir are used in the production of plywood, but many other varieties are used for the front side of decorative panels. Plywood is available in several thicknesses and sizes, of which the flooring of the body can be made in one piece.
Block Board.
There are several made boards using solid wood. One of them is a block board, and it consists of conifers glued together and veneered with wood veneers, such as birch and mahogany. Large panels up to 2 inches thick are manufactured and used in floors and partitions.
LDSP.
Chipboard is made of graduated wood chips, which are connected together under pressure with synthetic resins and adhesives to form large, strong panels with a thickness of 0.5 inches to 1 inch. They can be lined with a variety of different materials for applying painted, plastic or veneered surfaces. It has replaced solid wood for many purposes, and because of the fabricated dimensions, it is a useful building material for vehicles.
Medium Density Fiberboard (MDF).
MDF is made by gluing wood fibers together using glue, heat and pressure. It is a highly adaptable material, but it can only be used for internal bodies. It must be sealed / colored as it usually emits urea formaldehyde, which is a known carcinogen, eye, throat and lung irritant. Proper security procedures should always be used when handling this material.
Hardboard
This is another useful material that, due to its smaller thickness, is very suitable for interior plating. It is made of compressed wood fibers and usually has a smooth side with a reverse side having a rough or mesh finish.
Wood identification.
Since many types of wood are used in the bodywork, it is possible to identify more common ones, such as oak and teak. Most types have different features and properties, and when samples are thoroughly checked, it is often possible to determine a specific type. The following features should be considered:
1. General view.
- i) Color - red, brown, yellow, white.
- ii) Grain - close or open, straight or twisted.
- iii) Texture - hard or soft, rough or smooth.
- iv) Drawing - grain shape
2. Weight.
Weighing a sample is not a reliable test, as the weight will depend on the moisture content, and even the weight of the samples may vary.
3. Use a manual lens.
Consideration of the surface and final grain may reveal distinctive features.
4. Use a microscope.
Using a microscope will allow a much closer look at the thin section.
5. Dissolving the sample.
This will allow a microscopic study of the shape and size of cells and fibers.
It should be remembered that the origin and growth rate and treatment after cutting and many other factors can affect the properties and color.
Wood defects.
One of the main disadvantages of wood is that defects may be present or may develop later. Some of these may be handled satisfactorily, but others may require component replacement. Some defects can be completely avoided by careful feeding, conversion and seasoning, but knowing the defects will allow you to make the most of your wood, which may be somewhat lower.
Nodes.
They are not always a serious defect, as in many cases wood is covered with paint, panels or other masks, and in woods such as knotted pine, they are processed to improve the appearance. On the other hand, knots should not be present in a frame of logs, some decorative panels, or other situations in which force or appearance can be affected. Nodes are almost always present, and wood is often evaluated by the distribution and number of nodes present. Some logs have more than others, so careful selection is usually worth it.
Splits and shakes.
Shakes appear in various forms and are not always noticeable until the tree is filled and sawn into logs. Heart and cup cocktails may not be a big problem, but other types, such as rings and asterisks, can cause valuable wood to become unusable. During drying or seasoning, moisture leaves wood faster than the ends than the sides. If it is too fast, other splits may occur.
Woodworm.
Different types of wood are exposed to various insects, and chemical treatment can be effective. An alternative is to remove and incinerate the infected part and install a new part.
Dry rot.
Wood stored in wet or inadequate ventilation loses its strength and becomes soft and spongy. If this happens, the wood must be destroyed.
Curvature.
This is a common defect and is caused by uneven shrinkage during seasoning. Conifers are more prone to this, because conifers contain more moisture than hardwood. Warping can be reduced by cutting logs radially, rather than indirectly. If you investigate the final grain of the boards, then you can decide how they were cut from the magazine.
Causes of wood defects.
- i) Storm damage.
- ii) Open growing conditions.
- iii) Inexperienced felling.
- iv) Incorrect conversion.
- v) Bad seasoning.
- vi) Poor storage conditions.
- (vii) Careless selection and use.
Seasoning.
Living trees can have moisture from 50% to 100%, and because it is too high, the trees should be dried or dried during filling until the moisture content decreases. Wood for the body should have a moisture content of 12-15%. If the moisture content is too high, the wood will dry out and shrink after use. If it is too low, the wood will absorb moisture from the atmosphere and possibly swell. To find the moisture content, the wood sample is weighed in the normal state, and then weighed again after careful discharge. The moisture content is then calculated as follows:
Moisture The wood content (MC%) is calculated by taking the wet weight, subtracting the dry weight and dividing the response by the dry weight and multiplying by one hundred.
The method of drying a piece of wood to obtain moisture in practice is not needed, since electrical appliances are used for instant reading. There are several reasons why wood should be properly furnished (seasoned): -
- I) It is much stronger than reckless wood.
- Ii) There is less risk of insect decay and attack.
- Iii) Painting, painting and other finishing processes can be successfully transported on test wood.
We must remember that the cells in a piece of wood are like wooden buckets. There is a large amount of water in the cavities and walls, so it is important that the wood is properly seasoned. After the trees have been filled, the logs are taken to the sawmill station, where they are converted or sawn into boards or other sections. Since this creates a large surface area for the atmosphere, the exposure time is reduced. The method used to view or transform logs will also affect shrinkage, deformation or other wood defects previously.
Air drying.
Timber is stacked in stacks with chopsticks or wooden strips separating each layer. This allows air to circulate freely around each part. The top of the stack must be protected from the sun and rain, and since moisture dries faster from the ends of the boards, they are sometimes protected to prevent breaks in the ends. The method of drying in the air is cheap and often results in better quality lumber, but this is a slow method, calculated over several years. Wood is susceptible to staining and attacking insects, and the moisture content is very rarely less than the surrounding area.
Drying in drying.
This is a much faster method, which leads to wood with more controlled humidity. The wood is placed on carts and placed in a furnace, where temperature and humidity are controlled. Air circulation can be caused by a natural bout or forced by electric fans. Artificial sawn timber may be more fragile, and other defects may occur, but the required reduction in time is a big advantage. Some wood materials are released by air during the period prior to kiln drying.
Wood storage.
The wood refueling process can take several years, and the wood can be stored for the next period until it is used. To keep it in good condition, certain precautions must be taken:
- i) To prevent staining, wood should be protected from chemicals and other foreign substances, such as soot.
- ii) Excessive rain and heat should be avoided, and when stored indoors should be provided with adequate ventilation.
- iii) It must be laid properly to prevent the boards from twisting or deforming. The supporting blocks must be directly under each other, otherwise the wood will begin to bend.
Wood preservatives suitable for use before coloring.
This type of conservator usually has a low viscosity and can usually be used before applying the trainer or decorative enamels and their painting process. It can be applied with a brush, spray or dipping and is usually allowed to dry overnight before applying the above mentioned paint systems. It promotes good adhesion and helps reduce the problems of forest and rot diseases.
Before using this type of product, you must ensure that it does not contain waxes or silicone additives.
Priming wood.
Before priming any wood, it is important to check that the wood is clean, dry and free from oil residue. The wood should be carefully leveled with suitable grade paper and degreased without using anhydrous water. a cloth moistened with white alcohol or a suitable solvent.
Priming should then be transported using a suitable primer. It is very important that all areas are completely primed when backfilling. This includes wood ends and tongues and grooves where the areas should be covered with metal parts or body sections. The reason for this is to prevent the ingress of moisture, which can lead to peeling paint.
Woods containing knots should be treated as follows before priming:
I) Nodes should be burned with a blowtorch to extract excess resin.
Ii) Wood should be thoroughly cleaned and degreased as described above.
Iii) Each node should be treated with one or two layers of shellac and leave enough time to dry.
Iv) Prepare the wood as above.
Wood trim.
These are non-pigmented finishes. Wax policies, sealants, long and short oil-based varnishes, alkyd varnishes, varnished varnishes, one-component polyurethanes and teak oil are available. All are suitable for brushing. For spray-only application, use the following - cellulose varnishes, two-component polyurethanes, two packaged catalyzed varnishes, and one- and two-component epoxy resins. The requirements of wood finishing are: -
- i) color flexibility.
- ii) Build.
- iii) Life expectancy.
- iv) Resistance to acid or alkali.
Seals and wax varnishes.
Sealers are cellulose.
Waxes - they are based on oil. One example is chilled wax, which dries quite quickly, gives a slight discoloration of wood and gives a good average finish.
Wax - on the basis of silicone. These waxes dry quickly and produce a tough waterproof finish. The wood must be sealed before use, and it promises to give it a cloudy look.
Waxes - Beeswax. This is a natural product of honeycombs, which was omitted by white alcohols. It can be applied with a brush or cloth and produce a good finish that can be re-polished.
Long oil paints.
They contain more oil than resin in its composition. The resin used is usually an alkyd or fossil resin. Long oil paints are flexible due to the amount of oil and have good durability, which makes it ideal for outdoor use. It also has a pretty clear conclusion. Polyurethanes are used for wood that remains in open conditions, but tends to be quite soft for indoor use. Life expectancy ranges from two to two and a half years, and it is recommended that the four-layer system, that is, apply one very thin (diluted) coating, and then three full layers.
Short oil Lucky.
These varnishes dry quickly, but tend to be quite fragile. They dry to a hard finish and are more suitable for internal use, as they do not have the flexibility for external use.
Alkyd varnishes.
These are transparent quick-drying varnishes that are suitable for indoor and outdoor use. They are popular as vehicle body varnish and are also used as a four-layer system.
Teak oil.
Это масло легко наносится, но для восстановления естественного цвета древесины требуются либеральные покрытия.
Французская полировка.
Это основано на шеллаке и метилированных спиртах. Он быстро высыхает и заставляет древесину темнеть. Он применяется с помощью подушки, сделанной из упакованного куска шерсти или марли, покрытой куском хлопчатобумажной ткани. Это, однако, хрупкое и легко повреждается водой и белыми спиртами. Он в основном используется в антикварной мебели.
Нитроцеллюлозные лаки.
Эти лаки бывают двух типов: предварительно катализируемые и нитроуретаны. Они содержат амино и полиуретановые смолы соответственно.
Conclusion.
Нет никаких сомнений в преимуществах использования древесины в кузове грузовых автомобилей сегодня. Разумеется, другие материалы имеют и придут, чтобы попытаться заменить его, но для его универсальности и доступности он по-прежнему не имеет себе равных и будет надолго.
Знание ваших пиломатериалов и порядок их ухода гарантируют максимальную продолжительность жизни вашего грузовика или коммерческого автомобиля.
