Furniture Surface Roughness

The wood surface after cutting will produce various surface unevenness, that is, roughness or smoothness, which will directly affect quality and appearance of the product. Therefore, it is necessary to strictly control the surface roughness of the workpiece to be within the allowable range .

1. The expression form of furniture surface roughness

(1) Saw marks and corrugated saw marks: There will be arc-shaped saw marks on the surface of the workpiece sawed with a circular saw blade, and oblique saw marks will be produced on the surface of the workpiece sawn with a band saw .

Corrugation: It is a wave shape with similar shape and size and regular ups and downs. This is the arc-shaped trace left on the surface of the workpiece after the surface of the workpiece is cut by planing, planing, and milling machines .

The size of the saw marks and ripples depends on the rotating speed of the cutter shaft and the feeding speed. The faster the rotating speed and the slower the feeding speed, the and the smoother the processed surface.

(2) Unevenness of elastic recovery Because wood is an anisotropic material, the density and hardness of each part are different.

Therefore, during cutting, under the action of cutting resistance, the elastic deformation of each part is inconsistent, and the amount of elastic deformation formed by the extrusion of the tool to the machined surface is also different. As a result, after the processing pressure of the workpiece is released, the recovery amount of the elastic deformation of the wood is different, and the surface is uneven, which is called the elastic recovery unevenness. Especially when planing and milling soft wood , the unevenness of elastic recovery is more obvious.

(3) Destructive unevenness is the unevenness . If the cutting amount is too large and the feed rate is too fast, it is easy to produce such unevenness. Generally, workpieces with defects such as dead joints, decay, and insects often have such unevenness during milling or turning.

(4) Unevenness caused by wood wool and burrs Wood wool means that one end of a single fiber on the wood is still connected to the surface of the wood, while the other end stands up or adheres to the surface. Burrs are bundles or sheets of wood fibers that have not been completely separated . Both affect the roughness of the wood surface. The formation of wood wool and burrs is related to the fiber structure and processing conditions of wood . Usually, wood wool is not included in the evaluation of surface roughness, because there is no proper instrument and method to make an accurate . In the process requirements for surface roughness, it is usually only indicated whether the presence of wood wool is allowed.

(5) Wood structure Since wood has conduits, large and small tube holes are formed on the surface. The roughness of the workpiece surface caused by such tube holes is called structural unevenness. Wood with thicker pores is called coarse-porous wood, and wood with smaller pores is called fine-porous wood. The thicker the tube hole, the rougher the surface of the workpiece will appear. On the cutting surface of the workpiece, the cut wood conduits appear as grooves or pits, the size and shape of which depend on the size and shape of the wood conduits and their angle to the cutting surface .

Parts and components made of wood particle board, ie, particle board, are also called structural unevenness due to the shapes of various fragments of different sizes on the surface and possible existence of insect holes, nail holes, cracks, etc. on the wood surface.

The surface roughness of furniture products is an important indicator for evaluating the surface quality of furniture. The surface roughness of furniture parts directly affects the quality of bonding, pasting and decoration of parts, as well as the amount of glue and paint.

Second, the main factors affecting the surface roughness of furniture

(1) Cutting amount The cutting amount includes the size of the cutter shaft speed, feed speed (feed speed), and the amount of cutting. The faster the speed of the spindle However, reducing the feed rate and reducing the amount of knife engagement can improve the surface finish, but at the cost of reducing production efficiency. Therefore, the surface finish of the workpiece is generally improved by increasing the rotational speed of the cutter shaft.

(2) The material, geometric parameters, manufacturing accuracy, grinding quality of the cutting tool and the smoothness will all affect the roughness of the workpiece surface processing.

(3) The rigidity, precision and stability of the machine tool——fixture——tool——workpiece process system The rigidity, precision, and stability of machine tools, fixtures, tools , workpieces, etc. are poor, which not only reduces the machining accuracy of the workpiece, but also It will also reduce the finish of the machined surface .

(4) The moisture content of wood affects the wood with low moisture content, and the smoothness of the cutting surface is better than that of wood . For wood with a high moisture content, the surface of the machined surface is prone to wood wool and shrinkage, resulting in a decrease in the surface finish.

(5) The cutting direction affects the cutting resistance of the workpiece along the wood fiber direction, which is smaller than that of the anti-fiber direction , and the smoothness of the cutting surface is higher. In the same way, the surface finish of the longitudinal cutting of the workpiece is higher than that of the transverse cutting , and the surface finish of the chord cutting is higher than that of the radial cutting.

(6) Other factors The chip removal status when cutting tools (such as square shell drills, planers) and other accidental factors (sudden increase in the amount of cutting or feed speed); the physical and mechanical properties of wood, such as hardness, density, elasticity, etc., will Affects the smoothness of surface machining .

To sum up, it is necessary to seek effective measures to improve surface finish . At the same time, it should also be emphasized that according to different quality requirements, the surface roughness , and the possible contradiction between improving the surface finish and improving labor productivity should be correctly resolved.

3. The influence of product surface finish on product quality

(1) Affecting product processing accuracy The higher the surface finish of furniture, the higher the processing accuracy and the higher the accuracy of measuring dimensions . Therefore, the higher the surface finish of the workpiece, the higher .

(2) Affecting the bonding strength of the product The higher the surface finish of the parts, the greater the bonding strength and the less the amount of glue used per unit area. vice versa.

(3) Affecting the quality of finishing The smoother the surface of the product, the clearer the wood grain, the more uniform the coloring, the stronger finishing quality.

(4) Affect the appearance of the product. The smoother the surface of the furniture, the more beautiful it will be, and it will produce a delicate and smooth aesthetic feeling.

4. Evaluation of surface finish of wood products

For the surface finish of precision instruments and precision machine tools, a series of precision photoelectric instruments can be used to detect , but whether it is feasible and necessary for the furniture manufacturing industry is still to be discussed. In the current wood processing and production enterprises It has not yet been adopted in , because the final surface finish of most furniture products is the finish of the coating film, which can be . In the current furniture manufacturing industry, the requirements for the surface finish of the workpiece are mainly guaranteed by the processing technology. The surface finish of the workpiece Rough finish means that the surface of the workpiece has only been planed, pressed, and milled , and has a finer wave shape. Fine smoothness means that the surface of the workpiece is planed, pressed, and milled, and then sanded by a coarse and fine sander or planed by a general smoothing machine. The surface basically has no wavy lines, only fine Linear sand marks or fine tears. Polishing, after planing, planing, and milling the surface of the workpiece, it is planed with a very precise and sharp manual planer or sanded with a very fine (00#) high-speed abrasive belt sand, and its surface cannot be seen with the naked eye. Sand marks and planing marks, feel very smooth.

At present, the inspection of the surface finish of workpieces by general furniture enterprises is based on subjective experience, based on seeing and touching, and workers or technicians with rich practical experience are responsible for the inspection. In actual operation, the detection method of drawing chalk is used, that is, to draw a stroke on the processing surface of the workpiece with chalk . What is obvious or absent is pure.