Successful repair or operation on new constructions with the use of the glue METAL-GLU is mainly dependent on proper preparation of the surface of the elements to be joined together that is cleaning, degreasing and roughening. The use of proper degreasing means (acetone or nitro-cellulose lacquer thinner), roughening by shot-blasting or sanding, by grinding pin, angular grinder, coarse or rasp file, coarse abrasive paper will give proper and strong joint of elements to be glued and strong adhesion of glue layer to the substrate surface. The recommended roughness is not less than 80- 130 micrometer what means that for shot- blasting or sanding the coarse fractions of abrasive material should be used. The element after roughening should be degreased again and dried.
Indispensable information to proper repair procedure or for designing new machines and systems is given below.
How to increase the adhesion and strength of the glue layer?
Making cuts and grooves on the surface to be regenerated in order to increase the bonding surface can especially enhance the adhesion of glue layer. Turning grooves, swallowtails, knurling cylindrical surface or shaping, milling or spot drilling on fiat surface can do it.
This type of working the substrate surface before glue application radically increases the strength of adhesive-bonded joint against shear and disruption.
Another important method to increase the strength of adhesive-bonded joint is the reinforcement of joint place using wire-mesh, nylon-mesh, fiberglass -, sisal- or cotton cloth. That type of strength scaffold for the joint (recommended on both sides of the housing, tank-plating etc.) makes the joint stiff and enhances the strength of the system very much.
Apply thin layer of the glue -in order to remove air bubbles.
Thin layer of the glue should be applied, of the thickness 0.7 mm, for heavy loaded adhesive-bonded joints. Remove air bubbles by pressing the glue layer with a spatula. As a result of application 3-4 thin layers one can be sure that the adhesive-bonded joint is not weakened by air voids.
Leakage from pipelines and tanks.
It is advisable to repair pipelines or heat exchangers under reduced internal overpressure, or better, at overpressure eliminated completely the system being repaired should be unloaded, if possible. First of all the leakage should be arrested by blocking holes with cork, plaster, sealing compound following the initial exact degreasing. Subsequently the first layer of glue should be applied fast and covered with a bandage, gauze or mesh. The second layer of the glue should be applied onto the bandage as soon as s lf the pipeline or heat exchanger will continue to "sweat" the procedure should be repeated two hours later. It means to degrease and apply the next layer of glue. It is advisable to blow warm air on the pipeline being repaired.
Repair of greased up tanks and machine elements.
Proper degreasing of the surface, which contacted to oil, is difficult- but the quality of repair is dependent on this cleaning operation because glue adhesion to the surface being joined is a deciding factor. The greased surface should be degreased several times using different degreasing agents. The final degreasing should be done using acetone. It is recommended to heat the greased element up intensively if the oil . or grease could penetrate into porous material. Heating by a local drier will squeeze the oil outside. It is also advisable to heat the element up in a drier before degreasing.
Repair of shaft.
Usually some defined places of the shaft need repair those are situated nearby sealing, sleeve, slide- or rolling bearing. The following procedure is proposed for repair of shaft:
1. Degrease the furrow in the shaft to be regenerated.
2. Undercut the shaft diameter by means of the lathe or grinder, recess of 1.5 mm for small shaft diameter and 2.5 mm for large shaft.
3. End the undercutting with swallowtail on both ends what will improve glue adhesion.
4. Do the screw on turned surface; use greater pitch of thread for greater shaft.
5. Degrease finally the place to be repaired.
6 Apply a thin layer of the glue METAL-GLU while revolving the shaft slowly and put the glue using a flexible spatula press it firmly to force the glue in the thread and remove air bubbles. Apply the glue in surplus of 1.5 mm in reference to the required surface of the shaft.
7. After final curing of the glue METAL-GLU (18 hours) turn the shaft roughly to the preliminary dimension with running speed up to 45 m/mm, at feed 0.2 mm/rev with bar turning tool made of sintered carbide, at the tool rake angle 6o. Subsequently, do finish turning at feed 0.1 mm/rev.
8. Polish the regenerated surface with water abrasive paper, cutting particles 400-600.
Repair of the splineway in the shaft.
1. Expand and deepen the worn out splineway in the shaft using grinding pin, grinder, miller or driller, provide roughness of the surface 80 micrometer minimum.
2. Degrease the shaft initially, roughen it again if necessary and degrease the splineway finally.
3. Smear the new spline with an anti-adhesive release compound, e.g., special silicon oil, silicon sealer or slightly with mineral grease.
4. Apply the glue METAL-GLU on the walls and bottom of the splineway and insert the smeared spline on proper assembling place; use spatula to remove the surplus glue that is pressed out by the spline.
5. Set the hub up on the shaft with spline and wait to the first curing of the glue- remove then the spline.
Repair of aluminum surface.
The layer of aluminum oxide should be removed from the surface by grinding, scraping or shot blowing.
Repair of cracks, pinholes and weakening of metal surface.
1. Drill holes at the ends of crack using the drill of diameter greater by 2 mm of the crack. lf the crack 5 a long one, drill several holes on the length the crack to destress the metal.
2. Splay the crack using an angular grinder or by spot drilling in V or Y form to increase glue bonding surface area.
3. Degrease exactly the place being repaired and remove all the filings.
4. Apply the glue METAL-GLU on the crack being repaired and press the flue firmly into the crack. Extend the glue layer beyond ends of the crack.
5. Cut a piece of wire mesh or made of fiberglass, nylon or rare cloth, a bit greater than the crack being repaired. Put the mesh onto the layer of glue and press it firmly to sink it in the glue.
6. Apply on the reinforcing mesh the additional external layer of the glue of 1.5-3 mm thickness and smooth the surface by hand or by means of a flexible spatula.
7. Grade softly the transition from glue layer onto metal surface.
8. Warming up the joint using a heater on lamp can accelerate glue curing. Remember that warming the METAL-GLU adhesive-bonded joint up to the temperature 60"C in 4 hours increases the joint's strength in 25%.
Glue injection to closed space.
A closed space of mechanism, e.g., chamber of a faulted bearing, blocks the repair and proper support of the bearing. However, you can do the repair by injection of diluted glue METAL-GLU (using the C agent), slightly warmed up, to the closed bearing chamber. A hole should be drilled in the bottom of the chamber. Additionally a venting hole should be done in the upper part of the bearing chamber. The bearing should be centered in the seat and fixed in proper position prior to operation. The glue can be injected using a large veterinary syringe (without injection needle) on be squeezed by a silicon paste applicator. It is advisable to wash the seat roughly using acetone and dry the chamber by blowing warm air prior to glue injection. It is a very economic method of repair large seats under large bearings.
Repair of heat exchanger's tube-sheet.
here in the tube-sheet of heat exchanger (e.g., condenser) are seated pipes, which mostly are made of copper or brass. An intensive galvanic corrosion may occur between copper pipe and steel tube-sheet. The heat exchanger can be saved by repair using the glue METAL-GLU. This way a large amount of capital can be saved that otherwise would be spent for the purchase on new complete equipment on for renewal of pipes and tube-sheets. Here is the proposed repair procedure:
1. Close the holes of copper pipes with matched plugs made of
rubber, cork or plastics so the plugs do not stand out more
than 1.5 mm from the pipe hole.
2. Do sanding of the tube-sheet with pipes being closed by plugs; coarse fractions of abrasive material should be used.
3. Blow out the residues of abrasive material using air compressor and degrease exactly the tube-sheet twice using a solvent, do not up set the plugs in holes of pipes.
4. Apply the glue METAL-GLU onto the tube-sheet in a layer of 2-3mm.
5. Wait 18 hours for curing of the glue METAL-GLU and remove the plugs using a screwdriver.
6. Grade the sharp edges of glue at the inlet to pipe using a cone cutter - it will improve the conditions of flow through.
7. Pay attentions during repair do not apply glue on the faysealing surfaces and ways in the heat exchanger.
Repair of scratches in cylinder liners and piston rods of hydraulic equipment.
1. Clean the scratch and deepen it using a drill, grinding wheel on cone cutter.
2. Do spot drilling at both ends of the scratch, using the drill of diameter 2-4 mm, to the depth 3-4 mm, to fix the glue joint at the ends.
3. Remove the filings and degrease the scratch again.
4. Apply the glue and after one hour remove the surplus glue from the surface.
5. After 18 hours grind in the surface being repaired using a fine grained abrasive paper.
Repair of extensive damage of machine body or construction.
An extensive damage of a main element of large machine, that can cause the loss of stability (e.g., breaking off a leg), should be repaired as given below. The traditional repair technology (degreasing, spot drilling or milling a gap, glue spreading, external banding, final glue application) should also include application of an additional reinforcement that can be done using flat iron fastened by screws at both sides of the crack. The reinforcement should be applied each 10 cm along the trace of the crack. lt is advisable to apply similar seams inside the machine body if a sufficient space can be found there. The applied seams of flat iron should be additionally glued bonded to the machine body after degreasing. The reinforcement of traditional joint as described above may save great and expensive machine from scrapping.
Repair of big rotor of centrifugal pump.
Rotors of pumps and other centrifugal machines very often have surface defects caused by hitting solid particles and from aggressive action of water on gas agent flowing through the installation equipment. Here is the proposed repair procedure:
1. Clean the rotor in a stream of water and degrease it.
2. Blow out the residues of abrasive material and weld a rod of 5-10 mm diameter (depending on the rotor diameter) to the worn attacking edge that is the agent inlet edge that will be used as a new, rebuilt inlet edge.
3. Weld a metal net to the existing non damaged surface and to the inlet edged formed by the welded rod.
4. Fill the voids with the glue METAL GLU (following the final degreasing of the rotor with the net and a new inlet edge); apply the glue onto the net and press it firmly by fingers to avoid forming air bubbles.
5. Smooth the surface of the blade with a spatula on by hand.
6. Apply a slightly warmed up glue on eventually diluted glue using the resin (C component) onto the whole surface of the blade, the thickness of glue layer being applied should be 0.5 - 0.7 mm, smooth all the surfaces by wet hand. It will be helpful to find and fill all the existing yet pinholes on rotor surface.
7. Check the critical dimensions of the rotor against the pomp body.
8. If the centrifugal machine operates at high revolving speed and the mass of the rotor is high - it is necessary to balance the rotor after repair.
Repair of internal surface of pump body and centrifugal machines.
The repair of sectional and non-sectional body of notating machine - pump, compressor on small
auxiliary turbine mainly concerns the internal surfaces of casting or welded housing. Those
surfaces are damaged from dynamic flow of the medium, corrosion action of water or by aggressive
fluids, by hitting solid particles immersed in the flowing medium or by galvanic corrosion
resulting from different materials of machine body and rotor.
The replacement of equipment, especially a large one, would be too expensive. On the contrary, the proposed repair using the glue METAL-GLU is fast, inexpensive and very effective. lt will also limit the galvanic corrosion because the machine body will be coated by the composition containing particles immersed in isolating epoxy resin. However, the repair needs a precise preparation of the surface and keeping exactness.
The following procedure is proposed:
1. In the case of a large machine body it is advisable to do sanding of the internal surface
using coarse fractions of abrasive material or mechanically roughen the surface using an
angular grinder. The residues of abrasive material should be blown out using air compressor.
2. Degrease exactly the internal surface of the machine body.
3. Fill all the worn surfaces with the glue.
4. Smooth the surface of the glue with a spatula or by rubbing the surface by wet hand (the moisture will reduce friction between hand and glue) doing circular movements of the hand to smooth the layer of the glue METAL-GLU being applied.
5. Check the critical dimensions of the pomp body to provide free revolving of the rotor.
6. It is recommended for joint strength to apply the glue in two on three layers, pressing the glue firmly to force it into the pinholes. Apply the glue in surplus of 0.5-0.8 mm in reference to internal surface of the machine body, do not exceed the critical dimensions (see point 5).
Other applications of the glue METAL-GLU.
1. Fast repair of cisterns and transportation tanks even on the transport route.
2. Repair of screw propellers of vessels (as rotors of centrifugal pumps).
3. Repair of corroded metal pipes using the method glue + bandage + glue.
4. Repair of cracked valve bodies.
5. Repair of damaged servo piston rods and cylinders.
6. Repair of damaged ways and races of machine tools and machines.
7. Repair of decrements on reinforcing corroded bracing on vertical walls of construction, this is possible owing to thixotropic properties of the glue, it means there is no flow of glue on vertical surface.
8. Repair of corroded surfaces of complicated shape, e.g., feeding screw or bucket conveyor, etc. The repair can be done after preparation of models of the surface for further shaping the glue layer.
9. Manufacturing by means of the glue moulds for casting plastics, gypsum moulds, making patterns , prototype models etc.
10. Fixing mutual position of elements, e.g., screw vs. nut using slightly thinned glue.
11. Fastness to acid or alkali of particular equipment and tanks can be increased by application give layer onto the parts of machine body, castings, sheets those are subjected to aggressive fluid; the repair method as for the body of centrifugal pumps.
12. Owing to the high compressive strength of the glue METAL-GLU (1000 kG/mm2) we can repair disturbance of machine foundation and other equipment by raising them and making from glue putty an additional foundation mat under elastic elements those are situated under the machine body.
13. The glue METAL-GLU can be applied to join the lumps of stone, marble, ceramics, semi-vitreous China ware, glass or to join those materials with metal parts.
14. There is possible a wide application of the glue METAL-GLU in steel engineering because the glue can be used to join rolled metal sections and sheets.
Using METAL-GLU in steel structures and pipelines.