From time to time, every technologist is faced with a situation where securing workpieces for machining is not an easy task. There are types of parts, the fastening of which to the machine each time requires considerable ingenuity:
- case parts with thin walls (fastening in a vice leads to warping);
- workpieces processed along the contour (mechanical clamps close the processing area);
- thin-sheet workpieces (lack of uniform fastening of the contact surface);
- soft or brittle materials that easily break under load (wood, plastic, glass, etc.)
- large-sized parts of complex shapes that require a lengthy process of fastening using sets of mechanical clamps (for example, aircraft panels);
- workpieces, the processing of which is advisable in one installation without readjustment;
- securing sheet non-magnetic materials;
- securing ultra-thin materials (foils) used in manufacturing and assembly printed circuit boards and radio-electronic components.
To solve these problems, each enterprise has its own sets of equipment, special processing techniques are developed, and special tools are often used. However, in the world there are two technologies for fastening such parts, which significantly facilitate the work of technologists. This fastening is due to magnetic field and using a vacuum. Magnetic tables are widely used and the principle of their operation is clear. Technology vacuum fixing blanking is currently just beginning to be mastered at Russian enterprises, often solving complex tasks that were difficult or impossible to perform by other methods of fastening. One of the main advantages of vacuum clamping is the uniform distribution of the clamping force over the entire area of the workpiece, which avoids vibration during machining.
The operating principle of vacuum tables is based on creating a vacuum between the workpiece and the supporting surface of the device. In this case, the entire part is subject to a pressing force equal to atmospheric pressure, which under normal conditions is equal to 760 mm Hg. Art., and is about 1 kgf/cm2. That is, a pressing force equal to 600 kgf will act on a plate measuring 20x30 cm! And this force will increase in proportion to the area of fastening.
Vacuum is created by vacuum pumps of varying power depending on the type and size of the table. Modular devices allow you to work in conditions of coolant supply to the processing zone.
As an example of a minimum set of all the necessary components for the full operation of the vacuum system on a machine, we can cite the “starter kit”. This kit includes a vacuum pump, a lattice modular table measuring 200x300x32.5 mm, an adapter (adapter board) for VAC-MAT mats, VAC-MAT mats (10 pcs.), everything necessary elements table fasteners and vacuum connections.
This vacuum system allows you to fix and process any flat workpiece, the contact surface of which does not exceed the area of the vacuum table. Thanks to a special adapter, it is possible to perform through processing of workpieces from one installation.
Lattice vacuum tables.
The most common type of vacuum tables. A seal is placed in the grooves of the grid along the perimeter of the workpiece being processed, forming a closed loop. Then the workpiece is installed and based on the eccentric stops. When vacuum is applied, the workpiece is pressed tightly against the table surface.
Tables are manufactured in various designs. Modular tables can be connected to each other, forming a large mounting area. Circular tables are designed to secure rings and round blanks. The vacuum hose can be supplied either from the end of the table (standard design on milling and grinding machines), and in the center (fastening to rotary tables machining centers and in lathe chucks). There are a number of standard table sizes available from aluminum alloy or steel (option for magnetic tables of machine tools), but often the size of the vacuum table is determined by the dimensions of the machine table.
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Vacuum tables VAC-MAT.
Tables for working with rigid polymer mats VAC-MAT. The design of the mats allows air to be pumped out from the volume of many chambers formed between the workpiece and the polymer mat. As a result, through processing of workpieces becomes possible (making holes, windows or going around the contour of a workpiece from one installation).
All mats have standard size 300x200x2.5 mm, but differ in rigidity, which ultimately affects the manufacturing accuracy of the workpiece being processed. Mats are consumables and are replaced when damaged by a cutting tool. As a rule, one mat is used for through processing of parts of one type. When switching to another type of parts, the mat is replaced. VAC-MAT tables can be made in various designs, including, as in the case of lattice tables, modular. There are also adapter boards that can be installed on grid tables to work with VAC-MAT mats.
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Vacuum groove tables
This type of vacuum tables is designed for securing workpieces with a small contact area (small products, workpieces with a large number of holes and windows). The use of flat mats with a high coefficient of friction makes it possible to create additional force from the shear of the workpiece relative to the fastening plane.
A flat mat is placed on the plate, in which holes are knocked out, located under the supporting surface of the workpiece, as shown in the figures. When secured, the workpiece is pressed tightly against the mat. On these tables, just like on the VAC-MAT tables, through-processing of workpieces is possible. After perforation, the mat will serve as a template for fastening and processing similar parts.
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Vacuum tables FLIP-POD
FLIP-POD vacuum tables have been developed for clamping large workpieces. Clamping with this system allows processing of the end surfaces of workpieces using vacuum suction cups (FP elements).
Each FP vacuum element operates as an independent valve. When the element is turned to the suction-up position, it is included in the vacuum channel (working position); in the suction-down position, the FP element takes its place inside the table and turns off the vacuum supply. Height-adjustable FP elements allow you to expand the range of workpieces to be fixed.
The dimensions of the boards and the location of the FP elements are selected based on data on the machine table and the task performed on it. Exist different kinds additional elements for basing workpieces. The vacuum table can be attached to the machine table using side clamps or directly through special mounting holes.
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Vacuum tables made of porous materials designed for machining without coolant of thin sheet materials right down to the foil. Homogeneous porous structure work surface vacuum tables forms an area within which the workpiece can be placed on stops and secured without additional operations to readjust the table to a given shape of the part. The workpiece can be of any configuration. The pressing force in this case will depend on the total area of the contact surface of the workpiece and the board, as well as on the quality of processing base surface blanks.
Porous table blocks are made of various materials, different in structure and properties (pressed materials with a homogeneous porous structure and sintered metals: bronze, steel, aluminum). The selection of material is carried out by specialists based on data on the workpieces being processed. It is possible to produce vacuum boards with a working surface tolerance of 5 microns along the plane. Boards can be made to a given size or in the form of connectable modules. Porous materials can be supplied separately as blocks maximum size 500x500x400 mm. If necessary, obtain bigger size blocks can be glued into sheets. After gluing, the sheets are subjected to secondary mechanical processing to obtain the required surface accuracy.
This type of board has proven itself in high-precision engraving thin plates and securing foil in the production and assembly of printed circuit boards, solar panels and radio-electronic components. The foil is securely fixed, straightening out on the working surface of the board with a plane tolerance of up to 2 microns.
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Components for vacuum systems
Selection of a vacuum system consists of selecting or designing a clamping device (board) of the types described above, in accordance with the technical specifications; the right choice vacuum pump or a modular device and other elements that ensure reliable supply low pressure from the pump to the board.
PTC VECTOR LLC is the official representative of the world's leading manufacturer of such vacuum fastening systems, HORST WITTE GERÄTEBAU (Germany). Our specialists have significant experience accumulated during the implementation of these systems at Russian enterprises. We are ready to answer any questions and provide qualified assistance in solving complex technological issues.
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COLD FIXING TECHNOLOGY
The technology for fixing workpieces by cold is an innovative approach to solving complex problems of fixing workpieces without mechanical impact:
- fragile workpieces (ceramics, plastic, glass, polymer materials, etc.);
- small workpieces from any materials;
- cellular materials made of aluminum and fiberglass used in aircraft construction.
Fixing is done on a freezing board, on the working surface of which a thin layer of water is previously sprayed or a special gel is applied. During the fastening process, the water layer freezes and a thin ice film is formed, which firmly holds the workpiece on the working surface of the board. In this case, the workpiece does not experience mechanical stress and is not deformed. To remove the workpiece, it is enough to switch the device to the heating mode of the working surface.
This technology successfully used in machining on milling, turning and engraving equipment. There is one limitation for all devices - when using, the supply of coolant to the processing zone is prohibited. by the company HORST WITTE Two types of cold fixing systems have been developed:
AFP (Air Freeze Platte) systems
Cooling of the working surface of the board occurs due to the thermodynamic process occurring inside the board when a pressure of 6 atm is supplied. This does not require additional cooling stations. The system consists of a freezing device and a polymer tube. The size of the working field of the device ranges from 100x140 mm to 140x150 mm. Temperature range in cooling/heating modes -10/+10˚С. To make it easier to change workpieces, there may be several cooling plates included in one device. They are easily replaced on the fixture.
ICE-VICE systems
Cooling of the working surface of the board occurs due to antifreeze circulating between the board and the cooling unit. For one system with a cooling unit, it is possible to use 1-2 freezing plates with a working field from 125x150 mm to 500x500 mm. Temperature range in cooling/heating modes -35/+35˚С. The automatic cooling device controls and maintains the set temperature conditions.
A description of cold fixing systems can be seen on the pages of the catalog “Vacuum Fixing Technology”.
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Making a vacuum table is the most critical stage in constructing a thermal vacuum press with your own hands. At the design stage, it is necessary to determine the dimensions of the table, select the material for its manufacture, and think over ways to fix and seal detachable elements to maintain internal negative pressure (vacuum). The vacuum table is made with the same basic set of tools as.
Further in the text, we will call a vacuum bath a part of a vacuum table - a steel container, inside of which the workpieces to be coated are located, and from which air is pumped out. By working dimensions (dimensions) of a vacuum bath we mean its useful volume, measured by internal dimensions. We will agree to call the vacuum table the entire structure as a whole, consisting of a vacuum bath, an upper (movable) pressure frame, clamps and other smaller elements.
External and working dimensions of the vacuum bath.
Let's consider general principles choosing the size of the vacuum bath, we will designate specific numbers for our press.
The longer the vacuum bath, the more workpieces can be placed in it, or a larger workpiece can be veneered. On the other hand, the longer the bath, the more film has to be consumed in one working cycle, the larger the dimensions of the machine, which entails a greater consumption of room space. Need to find optimal size. As experience has shown, the optimal working length of a vacuum bath intended for the manufacture of standard furniture facades and decorative door trims, we can consider the value to be from 2.4 to 2.6 m. We will make a vacuum bath 2500 mm long, the working length of which will be 2500 - 40 x 2 = 2420 mm (40 mm is the width of the short wall profile pipe).
The width of the bath is directly related to the width of the PVC film used. Depending on the film manufacturer, there may be different widths; the most common is 1.4 m, which is what we will focus on. Let's choose the width of the bathtub to be 1400 mm, the working width will be 1400 - 40 x 2 = 1320 mm. When facing tall workpieces, for example, for curved (radius) facades, the width of the bathtub must be reduced (made smaller than the width of the film), but to work with such workpieces a press of a different design is needed, so these issues will not be considered.
The working height of the bathtub should be calculated based on the requirement that there is a small free space between the upper surface of the facades and the covering film. In other words, the film stretched over the workpieces should not touch them before air is pumped out. The calculation is as follows. Firstly, the vacuum (breathable) tabletop, which will be the first to be placed on the vacuum table, will be made of 10 mm thick MDF board. Secondly, the linings for the facade blanks will be small pieces of MDF board 16 mm thick (this is the simplest, most common and best option linings). Thirdly, the thickness of the veneered blanks will range from 8-10 mm (door linings) to 16-32 mm (facades and other furniture elements). Fourthly, the sealing rubber will add about 2 mm to the depth of the bath. As a result, the maximum height of the entire “pie” inside the bathtub will be: 10 + 16 + 32 = 58 mm. To make a vacuum bath, we will use a profile pipe with a cross-section of 60x40 mm, placing it on the short side. At the same time, the height of the free space will be no less than: 60 + 2 - 58 = 4 mm, which is quite enough.
Making a vacuum table.
Vacuum bath.
The bottom of the vacuum bath will be a sheet of steel 2 mm thick. To minimize the deflection of the sheet under the influence of negative internal pressure, and to give the table surface an even shape (close to an ideal plane), it is necessary to make a rigid frame. To make the frame we will use the same profile pipe 60x40x2. The pre-cut pipe, in accordance with the design, is laid on the slipway, rigidly fixed with clamps, and all connections are welded. After making the stiffening frame, a steel sheet is welded on top of it. This is the most critical stage welding work, it requires a continuous weld to be hermetically sealed (double penetration is recommended).
To avoid warping of the sheet under the influence of prolonged high temperatures, you can use the following alternative method of welding the sheet to the stiffener frame. Before laying the steel sheet on the stiffening frame, it is necessary to apply a sealing compound around its perimeter that can withstand high temperatures(for example, silicone high-temperature sealant), and welding is carried out not with a continuous seam, but with small regular fixing tacks with a pitch of about 50 mm. This method is designed to ensure that short-term, local welding effects will not damage (burn out) the entire sealant, but only a small part of it in the immediate vicinity of the tacks, while most of the sealant, after curing, will perform its direct function.
Vacuum table dimensions.
Detailing of the stiffening frame and the procedure for assembling the vacuum bath: the stiffening frame is welded, a steel sheet is welded to it, a stationary (lower) frame with a part of the hinge joint for attaching the lifting (upper) frame is hermetically welded around the perimeter of the steel sheet.
Photo of the vacuum table from below.
The stiffening frame is made partly from an angle profile.
Lifting (clamping,top)frame.
Frame material - profile pipe 60x40x2 mm. The dimensions of the pressure frame must be exactly the same as those of the vacuum bath. If it was not possible to find a sufficiently even (not bent, not twisted) profile, then it is necessary to pre-select in pairs several of the smoothest rods from which the parts of the vacuum table will be made tightly adjacent to each other.
The clamp frame will rise thanks to adjustable hinge joints. The adjustment of the hinges is carried out after gluing the seal - strips of sheet rubber of medium hardness, about 2 mm thick.
Welded washers are needed to increase the friction area. The hinge pin is a D12 steel rod with threaded ends.
To hold the clamping frame in a raised state, gas lifts can be used. For safety reasons, it is recommended to install four gas lifts (two per side) and ensure that any three of them can support the frame. If the opening angle of the frame (45°) turns out to be insufficient, the frame will cause significant inconvenience in operation; it can be raised as high as possible at an angle of slightly more than 90°, using the thermal module parked behind as a support (gas lifts are not used).
Clamps.
To securely and tightly hold the film during vacuum pressing, it is necessary to firmly and evenly press the upper frame to the perimeter of the vacuum bath, ensuring that the rubber seal fits everywhere. For these purposes, you can use various ready-made clamps, or make them yourself.
For the manufacture of homemade clamps working on the eccentric principle, you will need the following rolled steel: half a meter of DN50 pipe (external diameter about 60 mm), two meters of rod with a diameter of 10 mm, and approximately the same amount of profile pipe with a cross-section of 20x20x2 mm.
Firstly, the DN50 pipe is cut into 8 equal 60 mm sections. Each pipe section is finished with a semicircular central cutout having a width of 10-11 mm and an arc length equal to 3/4 of the length of the outer circumference of the pipe. We get 8 pieces of eccentric rotary cylinders, to which we need to weld a handle 220 mm long from a square profile 20x20 mm.
Secondly, the steel rod is cut into 16 pieces: 8 pieces 190 mm long (for studs) and 8 pieces 55 mm long (for king pins). An M12 nut (or M10 with a drilled thread) must be welded to one end of the stud so that it can rotate freely on the pivot, and an M10x50 thread must be cut at the other end.
Thirdly, to complete the manufacture of the clamp, we weld the ends of the pin (with a nut with a welded pin pre-attached to it) to inner surface eccentric rotary cylinders.
To install clamps on the vacuum table of the press, at eight points of the table, according to the project, drill through holes with a diameter of 10 mm. After which, the upper holes are enlarged, giving them an oblong shape. The clamps are adjusted by installing combination nuts in the desired location on the stud thread, followed by fixing them with locknuts. This operation is performed on last stage manufacturing a vacuum table, after gluing the rubber seal.
Elements and dimensions of the hinge clamp.
The hooks for the clamps are made from 50x50x3 angle steel.
If it was not possible to achieve a flat table surface.
If during the welding process the sheet has undergone significant deformations that go beyond the permissible values, then there is no need to pick up a grinder and cut off the welds and redo everything again. You can ensure a perfectly flat plane of the vacuum table additional measures, namely through the use of epoxy leveling compounds, which are used in the manufacture of poured floors. To do this, the vacuum table is set strictly according to the level, the required volume of the filling mass is determined (for example, by test filling with water), the bottom of the vacuum bath is cleaned of rust, and it is primed. Fill with the prepared epoxy mixture according to the manufacturer's instructions. For reasons of economy, the mixture can be diluted with some cheap filler, for example, quartz sand. To speed up the curing of the mixture after pouring, the table can be controlled from above with heat from the thermal module. It makes sense to carry out this filling leveling operation after the vacuum press is fully ready, test samples of products have been manufactured, and a decision has been made about the need to improve the geometry of the working surface.
Estimate for material for a vacuum table.
| Name | Length, mm | Quantity, pcs. | Purpose |
|---|---|---|---|
| Profile 60x40 | 2500 | 6 | Rigidity frame. Bath. lifting frame. |
| Profile 60x40 | 1380 | 4 | Rigidity frame. |
| Profile 60x40 | 1320 | 4 | Bath. lifting frame. |
| Profile 60x40 | 1001 | 6 | Rigidity frame (diagonals). |
| Profile 60x40 | 753 | 3 | Rigidity frame. |
| Profile 60x40 | 250 | 4 | Hinge. |
| Profile 60x40 | 180 | 2 | Hinge. |
| Profile 60x40 | 150 | 2 | Clamp support. |
| Profile 60x40 | 140 | 2 | Hinge. |
| Corner 50x50x3 | 50 | 8 | Lifting frame (clamp hook). |
| Profile 20x20 | 220 | 8 | Clamp. |
| Pipe DU50 | 60 | 8 | Clamp. |
| Rod D10 | 190 | 8 | Clamp. |
| Rod D10 | 55 | 8 | Clamp. |
| Rod D12 | 150 | 2 | Hinge. |
| Nut M10 combi | 8 | Clamp. | |
| Nut M10 | 12 | Clamp. Table fastening. | |
| Nut M12 | 16 | Clamp. Hinge. | |
| Washer d12 | 12 | Hinge. | |
| Bolt M10x60 | 4 | Table fastening. | |
| Sheet 2500x1500x2 | 1 | Table (bath bottom). | |
| gas lift | 2 | lifting frame. |
Upon completion of the main volume of work, the vacuum table is installed on the frame (on specially provided supports) and fixed in the corners with four bolts, as shown in the figure, after which proceed to small jobs: installation and adjustment of clamps, adjustment of the lifting frame hinge, gluing the seal.
The metal structure is beginning to take on the shape of a future thermal vacuum press, but it still lacks many elements: a vacuum system, a thermal module, an electrical control unit, which will be discussed in the following articles.
Company SOMMTEC has developed a line of perforated vacuum tables. A special feature of these tables are holes located at a distance of 10 mm over the entire area of the plate, which allows us to carry out processing at any point on the vacuum table. The open area of the slab must be covered with a continuous polymer mat to avoid loss of vacuum.
Perforated vacuum tables are manufactured in various designs. Modular tables allow you to create a large mounting area.
The main advantage of perforated vacuum tables is the ability to secure workpieces of complex shapes without additional reconfiguration.
SOMMTEC presents to your attention five series of perforated tables. Tables are used for processing metals, wood products, plastics, glass, film, foil, and engraving work.
All tables are made of high quality aluminum, the design of vacuum plates ensures high performance characteristics, as well as excellent geometric stability during long-term use, and can work in a humid environment when machining with coolant. The tables do not bend and have no internal tension; thanks to the developed channel system, it is possible to limit the working surface of the table. All perforated tables are equipped with perforated mats, which allows for through processing, as well as processing parts with existing technological windows and holes.
Vacuum tables MP series
Table Features:
- The table has M8 mounting holes with a pitch of 100 mm; it can be manufactured according to customer specifications;
- Hole diameter 0.3mm
- It is possible to install additional mechanical stops;
- The table is equipped with eccentric stops for positioning the workpiece.
| Pos. | Art.No. | Name | Dimensions, mm | Weight, kg |
| 1 | 15214112 | 216x136x26 | 4 | |
| 2 | 15324112 | Perforated vacuum table, raster 10 mm | 316x216x26 | 9 |
| 3 | 15334112 | Perforated vacuum table, raster 10 mm | 316x316x26 | 10 |
| 4 | 15434112 | Perforated vacuum table, raster 10 mm | 416x316x26 | 12 |
| 5 | 15524112 | Perforated vacuum table, raster 10 mm | 516x216x26 | 13 |
| 6 | 15544112 | Perforated vacuum table, raster 10 mm | 516x416x26 | 18 |
| 7 | 15644112 | Perforated vacuum table, raster 10 mm | 616x416x26 | 20 |
| 8 | 15654112 | Perforated vacuum table, raster 10 mm | 616x516x26 | 27 |
| 9 | 15754112 | Perforated vacuum table, raster 10 mm | 716x516x26 | 30 |
| 10 | 15154112 | Perforated vacuum table, raster 10 mm | 1016x516x26 | 50 |
| 11 | 15164112 | Perforated vacuum table, raster 10 mm | 1016x616x26 | 55 |
Special sizes are also produced upon request!
The package includes:
- Vacuum table;
- Perforated polymer mat;
- Solid polymer mat;
- Hose Ø12/18 mm 1 m;
- Stops;
- Description.
Perforated vacuum tables UPT series
The UPT series was developed specifically for processing thin materials such as foil, film, paper, plywood. The hole diameter is 0.6 mm, which allows flexible materials to be secured evenly.
| Pos. | Art. No. | Name | Dimensions, mm | Weight, kg |
|---|---|---|---|---|
| 1 | 15214.1112 | Perforated vacuum table, raster 10 mm | 220x160x24 | 5 |
| 2 | 15324.1112 | Perforated vacuum table, raster 10 mm | 310x220x24 | 9 |
| 3 | 15224.1112 | Perforated vacuum table, raster 10 mm | 222x262x24 | 7 |
| 4 | 15424.1112 | Perforated vacuum table, raster 10 mm | 400x200x24 | 10 |
| 5 | 15434.1112 | Perforated vacuum table, raster 10 mm | 430x310x24 | 15 |
| 6 | 15644.1112 | Perforated vacuum table, raster 10 mm | 610x430x24 | 21 |
| 7 | 15644.1112-2 | Perforated vacuum table, raster 10 mm | 600x400x24 | 20 |
| 8 | 15864.1112 | Perforated vacuum table, raster 10 mm | 850x610x24 | 48 |
| 9 | 15184.1112 | Perforated vacuum table, raster 10 mm | 1200x850x24 | 90 |
Using the power of a vacuum pump.
The milling machine work table itself is a horizontal surface that is designed for working with the part (it is fixed and securely based on it). This part of a milling machine is considered one of the most important - if the workpiece is not securely and evenly fixed relative to the movement of the cutter, then accurate and efficient processing will become unrealistic. Both the table and the cutting tool can move.
Milling machine work table with numerical control software It is equipped with longitudinal grooves where a number of clamps are placed to secure the part for processing or other necessary devices. But fastening with clamps has several disadvantages:
There must be mechanical clamping of the workpiece; the tightening force is set to the maximum.
Deformation and mechanical damage the front part of the manufactured part. Such consequences are absolutely undesirable for working with glass boxes equipped with backlighting - even the most minor scratches and cracks can completely ruin the appearance.
If the workpiece has some non-standard dimensions and shapes, then it is not always possible to select the required location due to the lack of symmetrical holes.
Difficulty with placement soft materials, which can bend when touched by a cutter (these are composite models with rather large dimensions). There is no way to install a large number of clamps on a table, so working with these types of workpieces is very difficult.
All of the above inconveniences can be solved quite simply - just install a vacuum table. It helps to securely fix the workpiece in the required place for precise machining with a milling cutter, without using mechanical clamps. The very essence of the work is that the air is pumped out, thereby reducing the pressure between the work table and the surface of the workpiece. This creates a kind of “suction cup” that firmly presses the part using atmospheric pressure. This helps to firmly and reliably fix the workpiece in the required position.
However, the vacuum table also has disadvantages:
– the impossibility of attaching very small parts or parts that are not sheet materials.
Usually, all manufacturers, when equipping a machine with a vacuum table, also leave the possibility of fastening with clamps, however, they are much smaller and they are no longer located as often as in a regular table.
– The compressor that maintains the vacuum requires a fairly powerful 5 kW, which usually leads to an increase in energy consumption, milling machine almost twice.
Therefore, every manufacturer must very carefully consider the pros and cons of vacuum fastening and make the choice himself.
Types of vacuum tables
Vacuum tables are divided into several types depending on the type of workpiece fastening:
Lattice. This type is most common, since it is easier to install and the cost is affordable. Thanks to its unique lattice design, it allows you to place required amount insulating material to enclose the workpiece around its perimeter. The pump pumps out air from the resulting circuit, thereby reliably pressing the part to the surface of the work table.
Vacuum tables VAC-MAT type. They are a rigid, durable frame made of polymer. It divides the space between the workpiece and the compactor into a number of sectors isolated from each other, from which air is then simultaneously pumped out. Thus, the vacuum is maintained even with the through type of milling; the compartments cannot be depressurized.
Slotted variety. They are indispensable when working with small workpieces, or with those parts on the surface of which there are many holes. Such a table is equipped with a number of grooves and compartments, some of which can be combined (if the holes match those on the workpiece).
Porous boards. They are recommended to be used for working with very thin material (like sheets of foil, for example). It can accurately reproduce the outline of the workpiece, the degree of impact depends on the area the “substrate” occupies. This vacuum material allows you to achieve high precision in processing and avoid errors. It is not permissible to work together with the coolant system.
Board type FLIP-POD. This a large number of separate suction cups-valves, which are designed for reliable fastening of even fairly massive workpieces. This system of vacuum tables does not involve covering the perimeter of the workpiece with a compactor, which makes it possible to process cutting tool edges of the part.
Almost all manufacturers of milling machines with numerical control offer the option of equipping their products with a special vacuum table. It is installed quite simply; there is no need to carry out any special operations or reconfigure the equipment - you just need to connect the compressor or vacuum pump.
Nowadays, you can see products everywhere that are made using technology vacuum forming. This approach allows you to quickly produce plastic dishes, packaging, mannequins, paving slabs and much more. To do vacuum forming at home, you will need a special machine. Such devices are expensive, and they are too bulky. This article will look at an example of creating simple machine vacuum forming, which uses only a vacuum cleaner and an oven.
Of course, the power of such a machine will be small, so it will not be possible to produce bulky objects or simply make a large number of products in a short time. But for the sake of interest and small household needs, such a machine is quite enough. In addition, with the help of such a machine you can perfectly make cases for various models, be it ships, planes or cars. You can also make elements for various homemade products. This device is a kind of original analogue of a “3D printer”.
Materials and tools for homemade work:
- vacuum cleaner (the more powerful, the better);
- oven (needed to heat the plastic);
- wooden blocks;
- drill;
- self-tapping screws;
- screwdriver or screwdriver;
- plywood or chipboard (thickness 16 mm);
- silicone (as a sealant);
- Fiberboard for the working surface (plywood is also suitable);
- aluminum tape;
- wood, plaster (or other materials to create a form).
Machine manufacturing process:
Step one. Vacuum machine dimensions
The main element of a vacuum machine can be considered a frame on which the plastic is heated, as well as a vacuum chamber. The dimensions of the frame should be such that it fits in the oven. You also need to take into account the size of the plastic sheets from which future products will be created. The frame is made of wooden blocks.
Step two. Making a vacuum chamber
The vacuum chamber is needed to “suction” the plastic, which, in turn, will envelop the mold underneath it. To make a vacuum chamber you will need chipboard sheet 16 mm thick or plywood. Technically, a vacuum frame is a box; its dimensions must correspond to the dimensions of the frame that will rest on it.
First, a frame is made from timber, and then plywood is screwed to its bottom. Since the chamber must be sealed, all seams must be coated with sealant during assembly.
The vacuum chamber also has a working surface, that is, the place where the products are formed. It is a sheet with evenly drilled holes. Fiberboard works well for these purposes, but plywood can also be used. It is important to understand that the working surface should not sag, so a spacer is installed in the center.
Step three. Connecting the vacuum cleaner
To conveniently connect the vacuum cleaner to the vacuum chamber, the author used a vacuum cleaner attachment. It needs to be screwed to vacuum chamber, having previously made a hole in it to pump out air. The nozzle is attached using self-tapping screws; it must first also be lubricated with silicone or other sealant.
If there are doubts about the tightness of the structure, it can be covered with aluminum tape or other adhesive tape on top.
Step four. DIY molds. Product creation process
To create a form you can use various materials, for example, gypsum, wood and others. If the forms do not have to be perfectly smooth, then polyurethane is ideal for these purposes, since it can be easily processed with a stationery knife.
If there are concave places on the form, then you need to drill holes here so that the plastic can be “sucked” into these recesses. A drill with a diameter of 0.1 - 0.5 mm is suitable.
Once the mold is made, you can proceed directly to the molding process. The work will be carried out in the kitchen, as access to the oven is required.
First you need to connect the vacuum cleaner to the vacuum chamber and place the mold in the center of the working surface. At the bottom of the mold you need to place spacers 1 mm thick; coins will do. This is done so that the plastic fits the shape at the bottom better.
Then you need to cut a sheet of plastic around the perimeter of the frame; PVC, PET and other types are suitable. Due to the fact that the vacuum cleaner does not create a very high vacuum, it will not be possible to use thick plastics. The thickness of the plastic for this homemade product should be in the range from 0.1 to 0.4 mm.
The sheet of plastic must be nailed with staples, maintaining a distance of at least 2 cm between them. There is no need to spare the staples, since heated plastic can easily break out of its fastenings.
Now you can place the plastic in an oven heated to 190 degrees (for each type of plastic there is optimal temperature softening). After some time, the plastic will heat up and begin to sag in the frame. Now it needs to be removed and installed on a vacuum machine. Subsequently, the vacuum cleaner turns on and the plastic begins to envelop the mold. When working, you need to use gloves, as the frame will be quite hot.
The vacuum cleaner needs to run for about 20 seconds, then the frame can be removed to remove the product. If in some places the plastic does not adhere well to the mold, you can use a hair dryer.
That's all, now the product can be processed at your discretion and painted in the desired colors. According to the author, such a homemade product can work without problems with a type of plastic such as polyethylene terephthalate, which is what bottles are made from. Well, what to do depends on the personal needs and fantasies of each homemaker.
