Gluing - Metalwork and assembly work. Gluing - Metalworking and assembly work Why glued parts are recommended tightly
— your guide to the world of scale modeling!
Work on a large-scale prefabricated model consists of a continuous connection of individual work stages - elements of construction and assembly. Just like an airplane is created at an aircraft factory. First one stage, then another. At the largest aircraft factories in the world (such as Boeing), the aircraft is generally located on a platform that continuously moves during assembly (from the beginning of the assembly shop to the finish).
And if we want to get a really worthwhile model — we need to improve the efficiency of each individual element of the assembly process. After all, if one element is bad, then maximizing the subsequent ones is much more difficult. If it makes sense at all.
Often a large number of shortcomings are caused by insufficient elaboration of the previous stages.
For example, you can spend all your nerves removing the joints of parts - glue seams, preparing the model body for painting. Often after such work it will be necessary to use a primer.
All this could have been avoided initially quality gluing of parts. So that the joint turns out neat, connection durable, and the seam - inconspicuous.
BUT HOW TO DO THAT?
Here you will need to use different types of adhesives.
In general, until a certain time I was not aware of the existence of different types of adhesives used in large-scale modeling. Typically using the simplest basic type of glue. The one we used to glue models back during the Soviet Union. And I didn’t pay any attention to the fairly rich assortment of model adhesives in online stores.
And only after taking a closer look at the work of Japanese modelers in the video materials of the Tamiya company - Tamiya Custom, I decided to look into this issue in more detail. I looked at what exactly they were doing. What adhesives are used and at what stages. Then I bought a little of all the glues. And started experimenting.
Several models have been used up different manufacturers to account for differences in plastic. After all, for example, Italeri’s plastic is different from Zvezdovsky’s. And the same Revell.
It turned out that all adhesives have their own specialization. This significantly improves the quality and efficiency of work. You just need to know the features of the composition and use of each individual glue. And break the assembly process into appropriate elements in advance - subassemblies .
So, let's look at all types of glue in order. And we will start from the very beginning level.
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| Glue for plastic models: Regular composition |
GLUE FOR ASSEMBLY MODELS: REGULAR
This type of glue is known to every modeller, because acquaintance with the creation of prefabricated plastic scale models begins with it. As a matter of fact, until a certain point this type of glue was used by modellers. Much later, Japanese manufacturing companies introduced other specialized types of glue into their product range.
In the Soviet Union, and later Russia, most modelers (especially mediocre modelers who collect models from time to time) use only it in their work throughout their many years of practice.
Therefore, this type of glue can be designated as universal standard .
Its main components are butyl acetate + polystyrene. Bonding is achieved due to the combined effect of the two types of action.
The first is the partial dissolution of the plastic on both bonded surfaces. When we connect the surfaces to be glued together and then leave them to harden, the dissolved plastic mixes with each other, connecting the edges of the parts together. The result is a “solid, single piece.” The joint is solid and durable. Ready for further processing.
This effect is also called welding effect .
The second is the additional fastening of parts with polystyrene particles included in the glue. They strengthen the molecular bonds in the dissolved plastic, helping to form a new solid compound.
The peculiarity of using this type of glue is that it is applied to the surfaces to be glued before joining the parts. Those. You must first apply glue to each joint surface. And only then put them together. For a better gluing process, you need to give the glue time to dissolve the plastic of each part separately. Wait 1-2 minutes. And only then connect the parts.
WORKING CHIP
While working on a model, many modellers have to deal with the situation of a thin, shallow recess appearing at the site of the glue seam. This is possible when the surfaces are not sufficiently prepared and the edges of the parts to be glued have an angle other than 90 degrees.
To avoid such troubles that border on the use of putty after drying, you need to do the following. During gluing, it is necessary not only to connect the parts, but to press them tightly against each other. Press one part onto another. As a result, the melted plastic will come out. Having fixed the parts in this position, leave them to dry. Then simply remove excess plastic from the joint surface with a modeling knife. And that’s all - the glue seam has an excellent shape that does not require additional processing.
There is one condition. You need to practice in advance on unnecessary details. Different plastics from different manufacturers have differences in their structure. Therefore, the same pressure can cause completely different effects. If you apply too much pressure, you can easily ruin the details of the model.
As always, caution and accuracy are important here. And preliminary preparation
GLUE FOR ASSEMBLY MODELS: SUPERFLUID
In general, the name of this type of glue should sound like “glue with increased capillary effect.” This is a liquid adhesive with very high penetrating ability, good volatility, high fluidity, without a consistent filler (gluing is achieved by partially dissolving the plastic on the surfaces to be bonded).
The main advantage of this type of glue is the possibility of penetration - flowing into the joint between folded parts . In other words, when working on a model, you connect the parts together and run a brush with glue along the joint. And thanks to its high fluidity, it independently penetrates into the joint. The action of this glue is fast. The welding effect appears very quickly. You won’t have to wait long for gluing and hardening either.
Often this glue is supplied in containers with a built-in brush. But if you use Akan Pro glue, you will need a brush. An ordinary brush, preferably synthetic. One or zero.
Another one interesting feature highly fluid adhesive is that when it gets on the surface of the plastic, it leaves virtually no traces when it hardens. It quickly evaporates, leaving behind a cloudy, rough surface. Which is not critical for further painting, and does not require a primer.
I would like to say a special word about the Akan Profi glue. It also belongs to the category of high-fluidity. But working with it requires a high degree of caution. He - " nuclear". It not only easily penetrates the plane of the joint of parts, but also very actively dissolves plastic. If you pour this glue onto a surface with potholes and uneven surfaces, it will cope with the leveling task better than putty. He Very good dissolves plastic. Tested on Ital and Zvezda.
Also, when using it, you must be careful not to spill it on the model. Pro only in very small doses does not leave any imprints. Even a medium-sized drop can be enough to form a molten recess.
It took me a long time to get used to this glue, but I liked its power. So I experimented further. Then, having found out its features of application in practice, I made it the main working glue in the process of assembling models.
In general, at the moment, high-flow glue is the main one for me when working on a model. Be it Akan Pro, or Tamiya ExtraThin Cement. I use regular glue only for joining large parts.
GLUE FOR ASSEMBLY MODELS: TRANSPARENT
In general, having considered the above types of glue, we could stop. After all, thanks to them we will be able to achieve solid results. But that would be wrong. There is another very specific type of glue.
T.N. "transparent glue" Its representative is “Contacta Clear” from Revell. Its only purpose is to glue transparent parts. Both with each other and with the plastic of the model itself. In fact, this is a variation of the same universal glue. Only there is no welding effect. Bonding is carried out due to the base, which becomes transparent when dry.
The glue is applied in a thin layer to the bonded surfaces of both parts. Then it needs to be allowed to dry for about 5-10 minutes (so that the adhesive layer is still sticky). Then we carefully press the parts to be glued together.
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| Glue for plastic models: Cyanoacrylate all-purpose glue |
GLUE FOR ASSEMBLY MODELS: CYANOACRYLATE
Cyanoacrylate glue, better known as “superglue”, which is the translation into Russian trademark Super Glue. This name became a household name in the former USSR.
Super Glue was first developed in 1942 (during World War II) by American chemist Harry Coover, who worked for Eastman Kodak, during experiments to find transparent plastics for optical sights. However, the substance was rejected due to excessive stickiness. In 1951, American researchers, while searching for a heat-resistant coating for fighter cabins, accidentally discovered the ability of cyanoacrylate to firmly bond. various surfaces. This time, Coover appreciated the capabilities of the substance, and in 1958, superglue went on sale for the first time, “exploding” the market.
In Russia, superglue is also sold under the brands “Clayberry”, “Sila”, “Cyanopan”, “Skley”, “Secunda”, “Monolith”, “Elephant”, “Super-moment”, etc. In the USSR, the glue was produced under the name “ cyacrine."
Adhesives based on cyanoacrylates can easily withstand loads of 150 kg/cm2, and more advanced ones, such as Loctite’s “Black Max” - 250 kg/cm2. The heat resistance of the connection is low and comparable to the heat resistance of acrylic plexiglass: from 70-80 °C for conventional adhesives, up to 125 °C for modified ones.
Cyanoacrylate is a strong, quick-setting, instant adhesive. Easily bonds non-porous and water-containing materials. It sets in less than a minute and reaches maximum strength after two hours. However, its shear strength is low, so superglue is sometimes used as a thread locker or for fastening a workpiece to lathe.
Information from the Wikipedia portal was used.
In large-scale modeling, cyanoacrylate, thanks to its ability to glue structures that are completely different in their properties, has also found its place - it has occupied its niche. We use it to fix photo-etched products and conversions created from epoxy resin.
Often we use super glue purchased from print shops or hardware stores. At the same time, the range of model chemistry manufacturers has long included specialized cyanoacrylate model adhesives. Although essentially their difference is only in the special packaging, convenient for the work of the scale modeler. So there is not much difference between them. And what to use - everyone decides for themselves, based on personal preferences.
It is worth considering that super glue has two types of consistencies - regular and gel-like. The second is thicker, jelly-like. It makes it easier to apply glue exactly to the gluing areas, avoiding drips.
GLUE FOR ASSEMBLY MODELS: EPOXY
Finally, it is necessary to mention two-component epoxy adhesives.
Their main property is that epoxy resin, when mixed with a hardener, forms a strong and very durable connection between the parts. But, in my opinion, they have not found wide application in the field of modeling using plastic prefabricated models.
This glue is suitable for wood and fiberglass models, wire parts, and photo-etching. But it is contraindicated for polystyrene models, since epoxy resin cannot adhere to plastic.
Epoxy two-component adhesives are also available in two versions - regular and modeling. One of the most interesting shapes The packaging of conventional cyanoacrylate variants has Contact glue. The shape of the tube allows you to squeeze out both the resin and hardener from two sections in equal proportions in one movement. They are automatically mixed at the outlet. Of the special modeling options, I know only glue from Tamiya.
But again, personally, I don’t see the point in using epoxy in our business. If anyone sees it, please reflect your opinion in the comments. It will be of interest to all members of our community.
At this point we have covered all types of glue used in scale modeling. What types of glue to use is, of course, up to you to decide. But to achieve a sustainable good result, the use of specialized tools is required.
Therefore, different model adhesives - BE !
That's all for today!
Good luck to you!
And wonderful models!
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>>Technology: Gluing wooden products
Gluing wood products
1 Prepare workplace to gluing the parts of the product you are making. Clean the bonding surfaces. Prepare glue and brushes.
2. Apply a uniform layer of glue to the surfaces to be glued with a brush, let it dry for 2...3 minutes, connect the parts and compress them with a clamp or in a vice.
3. In the next lesson, release the product from the clamp, make sure the gluing is correct, and clean the surfaces of glue.
- Natural (carpentry, casein) and synthetic (PVA, BF) adhesives, glue maker, clamp.
1. What adhesives are used in school workshops?
2. How are the surfaces of wood parts prepared before gluing?
3. Why do you think parts coated with glue need to be exposed to air before gluing?
4. Why is it necessary to tightly compress the surfaces to be glued?
A.T. Tishchenko, P.S. Samorodsky, V.D. Simonenko, N.P. Shchipitsyn, Technology 5th grade
Submitted by readers from the website
Gluing
TO category:
Metalwork and assembly works
Gluing
Gluing parts is the last type of assembly of fixed permanent joints, in which a layer of a special substance is introduced between the surfaces of the parts of the assembly unit that can firmly hold them together - glue.
This type of connection has a number of advantages: firstly, the possibility of obtaining assembly units from dissimilar metals and non-metallic materials, secondly, the gluing process does not require elevated temperatures (such as welding or soldering), therefore, deformation of parts is eliminated, third, the internal stress of materials is eliminated.
In plumbing and assembly work, adhesives are usually used: EDP, BF-2, 88N.
Like all other types of joints, the quality of glued joints largely depends on the correct preparation of the surfaces for the gluing process: they should not be stained with dirt, rust, traces of grease or oil. Surfaces are cleaned with metal brushes and sandpapers; the material used to remove grease and oil stains depends on the brand of glue used: when gluing parts with 88N glue, gasoline is used; for EDP and BF-2 glues, acetone is used.
The process of gluing parts consists of the following operations:
- prepare the surfaces of the parts and select the brand of glue (see above);
- apply the first layer of glue to the surfaces at the joints (this operation can be performed with a brush or by pouring), dry, apply a second layer of glue, connect the parts and press them together with clamps (here it is important to ensure the exact matching of the parts and their tight fit);
- hold the glued assembly and clean the seams from any glue smudges.
Drying mode for the first layer of glue: EAF - applied in one layer and does not require drying; BF-2 - 1 hour at a temperature of 20 degrees C (“touch-touch”); 88N - 10-15 minutes in air, “after applying the second layer, wait for 3-4 minutes and only then connect the parts.
Curing mode for glued joints: when using EDP glue - 2-3 days at a temperature of 20 degrees C or 1 day at a temperature of 40 degrees C; BF-2 glue - 3-4 days at a temperature of 16-20 degrees C or 1 hour at a temperature of 140-160 degrees C; glue 88N - 24-48 hours at a temperature of 16-20 degrees C under load.
When assembling machines and mechanisms, sometimes combined glued joints are used - glue-welded: a layer of VK-9 glue is applied to the mating surface of one of the parts, and the second part is welded using the spot welding along this layer.
In the designs of various machines and mechanisms that a mechanic has to assemble and repair, the main purpose of the moving units is to convert rotational movements into translational ones and to convert the speed and direction of movement. That is why such nodes are called transmissions. The action of mechanical transmissions is based either on the use of gearing (gear, worm, chain) or on the use of friction (belt, friction). However, both transmissions have something in common in their designs - the presence of bearings (sliding or rolling) in the transmission units. It is with their installation (installation) that we will begin to familiarize ourselves with the process of assembling mechanical transmission units.
Gluing is a method of joining workpieces using glue. By gluing it is possible to obtain connections from dissimilar materials. It does not cause structural changes in the workpiece material and does not make the product heavier. Adhesive joints have good heat-insulating, sound-absorbing, damping and sealing properties. The disadvantages of adhesive joints include low heat resistance and low strength. Many glues are toxic. By gluing, connections are made between bushings and housings or shafts, and also blanks made of sheet material are connected to each other.
Bonding is an adhesive process, i.e. the process of molecular adhesion of surfaces to glue.
The adhesive materials are high-polymers based on epoxy, polyurethane, phenol-formaldehyde and other resins. Adhesives based on epoxy resins (VK-32-EM, epoxy P, PR) are widely used. Connections with these adhesives are characterized by high shear strength and heat resistance (up to 90 ° C). Adhesives based on phenolic resins BF-2 and BF-4 provide lower strength and heat resistance up to 70 ° C. In units operating under conditions of elevated temperatures and vibrations, adhesives with high vibration resistance (VK-13, VK-13M) are used. Special adhesives provide heat resistance up to 500 °C and increased shear strength.
Sequence of work when gluing. For reliable adhesion, it is necessary to carefully prepare the surfaces for gluing. The gap should not exceed 0.05-0.25 mm. The strongest joints are obtained with a roughness of the bonded surfaces Ra = - 1.6 f 3.2 µm.
The workpieces are cleaned from dirt, scale and grease in solutions of phosphorus (low-carbon steel), sulfur ( aluminum alloys), nitric (copper alloys) acids and in alkali solution (corrosion-resistant steels). They are then washed in hot water, dried and degreased with solvents. Sometimes, before gluing, surfaces are subjected to tinning (brass), anodizing (aluminum alloys), etc.
The glue is prepared in special rooms. It is applied in individual dots, rows of dots, stripes or on the entire surface (in one or two layers). The workpieces are connected with clamps, clamps or special devices. Depending on the brand of glue and the shape of the surfaces to be glued, the pressure is 0.05-2 MPa. If hot curing is necessary, the workpieces are simultaneously heated in thermostats or ovens. The heating temperature and holding time are taken in accordance with those recommended for each brand of glue. After gluing, the remaining adhesive is removed with metal brushes, scrapers or sandpaper.
Repair of parts by gluing
New types of universal synthetic adhesives developed by Soviet scientists make it possible to firmly connect metals, wood, glass, plastics, friction linings, etc., both with each other and in any combination with each other.
The advantages of adhesives are relatively high bond strength, tightness, smoothness and cleanliness of the seam, lack of stress concentration, water-gasoline-oil resistance, acid-alkali resistance, corrosion resistance, elasticity and resistance to vibrations and shocks, electrical insulating properties and low complexity of repairs.
The use of adhesives in repairs is varied, for example: sealing cracks in engine blocks and cylinder heads, in crankcases, gluing friction linings of brake pads, clutches and clutches, replacing press fits on bushings, ball bearings, etc.
Before you start gluing, you need to select the brand of glue. The gluing process consists of pre-gluing, gluing and post-gluing processing.
Preparation for gluing. The surfaces to be glued must be well fitted to each other, clean and dry and slightly rough (treated with sandblasting, abrasive paper).
Cracks in plastic parts are packaged at an angle of 60-90° to a depth of 3-5 mm. The broken pieces are selected from scrap parts and adjusted.
For cylindrical joints between the bonded surfaces, it is recommended to make a gap according to the 5th class of sliding fit accuracy.
After adjustment, the surfaces are degreased with solvents.
Gluing process. The glue is applied to both surfaces to be glued with a glass rod or brush washed in solvent. The parts with the applied glue are lightly rubbed against each other, pressed tightly with a clamp and remain in this state until the glue has completely hardened.
Processing of parts after gluing. The glued parts are inspected to determine the quality of the bond. The thinner the seam, the better quality gluing. The entire space in the gluing seams must be filled with glue. After checking the quality, smudges and sagging are removed by softening the film with a solvent^ or, better, scraping with a scraper, knife, file, etc. The part can be processed on machines with and without emulsion.
If it is necessary to disassemble a glued joint, then the seam is heated to 200° and higher (until the adhesive film softens) and the parts are separated.
Gluing friction linings with VS-YUT glue. The previously used BF glue had insufficient heat resistance. When the temperature increased to 200°, the bonding strength was insufficient. As a result, BF glue is currently not used for gluing parts operating at elevated temperatures.
Currently, our industry has mastered the production of VS-10T glue, which provides the necessary joint strength at temperatures up to 300°.
VS-YUT glue - a solution of synthetic resins in organic solvents - is intended for gluing parts made of steel, duralumin, fiberglass, asbestos-cement and many other materials with each other and in combination with each other.
In structures operating at a temperature of 300° for 5 hours, VS-YUT glue provides high joint strength. Therefore, the existing riveting of brake linings to brake pads, clutch and friction discs can be replaced by gluing. At the same time, the service life of friction linings increases by 10-40% due to more complete use of the lining thickness. Gluing overlays is successfully replacing riveting in many farms.
The gluing process consists of cleaning the working surfaces of brake pads and linings, degreasing them, and applying adhesive. composition, pressing the lining to the block with a specific pressure of no more than 4 kg/cm2 and heat treatment (polycondensation and polymerization) at a temperature of 180° for 40 minutes.
Removal of the old glued friction lining is carried out by grinding with a cutter on a lathe or cutting with a wide cutter in one pass on a special device. Degrease the working surfaces of the pads or discs and the surfaces of the friction linings with gasoline, acetone, white spirit or other degreasing compounds. After holding at room temperature for 10-15 minutes to completely remove the solvent, work surface parts (disc pads) and the inner surface of the friction lining are applied with a brush with VS-10T glue in a layer of 0.1-0.2 mm. The applied glue is kept at room temperature for 25-30 minutes until the solvent contained in it is completely removed, after which the lining is bonded to the part.
When gluing the overlay, special attention should be paid to accurately performing the operation of pressing the overlay to the part. The required strength of the connection is ensured only if the lining is uniformly pressed against the part with a pressure of 3-4 kg/cm2 with simultaneous heat treatment under this pressure. To ensure the required pressure and uniform pressing, special devices are used, for example the device shown in Fig. 193. The linings are pressed to the pads with pressing rings made of spring heat-treated steel grade 65G.
Rice. 193. Device for pressing friction linings to brake pads: 1 - steering wheel; 2 - crimp ring; 3 - screw with left-hand thread; 4 - special nut; 5 - screw with right-hand thread; 6 - base; 7- special screw; 8 - movable cam; 9 - bushing; 10 - spacer; And - motionless cam
The pads, together with the crimp ring in a clamped state, are removed from the device for heat treatment in a drying cabinet, where they are kept at a temperature of 180° for 40 minutes.
For sealing cracks in the block and cylinder head, gearbox and gearbox housings and other parts in Lately Pastes (putties) based on synthetic resins ED5 and ED6 are successfully used. In liquid form, these resins are the condensation product of epichlorohydrin with diphenylpropane in the presence of caustic alkali. These resins are thermoplastic, but under the influence of various hardeners they turn into infusible polymers, which are used as a material for gluing protective coatings, producing cast parts and as sealants.
Cured resins have fairly high mechanical strength, good electrical insulating properties, high adhesion to metals, acid-alkali resistance, water-gasoline resistance and high heat resistance up to 300°.
To seal cracks in cast iron parts, a special paste is made, where ED5 or ED6 synthetic resin is the main binding material and makes up the largest mass. For this purpose in epoxy resin various plasticizers, fillers and hardeners are introduced.
The plasticizer dibutyl phthalate improves the plasticity of the paste, increases impact strength and flexural strength.
Organic fillers include wood flour, graphite, gas soot; they increase the volume of the paste, increase heat resistance and mechanical strength and reduce the coefficient of linear expansion.
Inorganic fillers are asbestos, quartz sand, porcelain flour, aluminum oxide, mica dust, etc.
Hardeners are anhydrides and amines, which accelerate the reaction between the paste and the base metal. Cold hardeners include polyethylene polyamine and hexomethylenediamine.
To prepare the paste, it is recommended to first prepare a four-ingredient paste. To do this, the resin is preheated to 60-90°, after which dibutyl phthalate is introduced, mixing it with the resin; then graphite and mica dust are introduced, stirring the mixture all the time. After introducing the fillers, stirring is continued for at least 5 minutes. The prepared mixture is cooled to room temperature and stored in a sealed container.
The technological process of sealing cracks in unloaded areas of cast iron parts is recommended to be carried out in the following order:
1. The area of the part where there is a crack is cleaned of dirt, oil and rust. The surface around the crack to a width of 20-30 mm is cleaned with an abrasive cloth until it shines.
2. At the ends of the crack, drill holes with a diameter of 4-5 mm, cut them and screw in brass pins.
3. Using an abrasive wheel from a hand-held electric drill, a groove of triangular cross-section with a depth of 0.75-0.80 of the wall thickness is cut (packed).
4. Finally prepare the required portion of pasta. To do this, the polyethylene polyamine hardener is added to the prepared four-component mixture in an amount of 10 wt. h. The paste with the hardener is thoroughly mixed for 5-6 minutes and at the same time the prepared area of the part is degreased with acetone or other fat solvents.
5. The paste is applied with a spatula into the packaged groove and left in this form to dry. The paste hardens at 20° within 24 hours. The process can be accelerated by heating the part.
6. After the paste has hardened, the part is subjected to a hydraulic test with water under a pressure of 3-4 kg/cm2.
7. If the parts can withstand this pressure, then the place where the crack is sealed is puttied and painted over.
This method of repairing parts is simple, reliable and cheap and can be recommended for field conditions and repair plants.
TO Category: - Maintenance of road vehicles
