What is Spray Welding?
Spray welding refers to a variety of welding processes that use thermal spraying. It is an industrial process in which a powder or wire is atomized with compressed gas at high speeds and sprayed onto a metal surface.
Spray welding employs industrial plasma, flame, detonators, arc spray, and high-velocity oxyfuel. Because of the significant heat generated by spattering welding, procedures and regulations must be strictly followed to avoid harm to people and the environment.
What is the Process of Spray Welding?
Thermal spray is a broad term that refers to a variety of coating processes. The entire welding process involves the use of coating material, such as a rod, powder, or wire, which is melted by various energy sources.
It is an industrial coating process that consists of a heat source and a coating material melted into droplets that are sprayed at high velocity. An atomization jet or gas propels the spraying toward a substrate.
Thermal spraying is a versatile process that is also known to be highly efficient. It can be an excellent alternative for a variety of surface treatments, including heat or nitride treatment processes, chrome, nickel plating, and anodizing, among others.
Individual preferences influence the thickness of the coating. The coating restores worn-out parts and basic machine components. It can also be used to improve the element’s performance and durability. If properly cared for, this can last up to 70% longer.
Different Types of Spray Welding Techniques
- Arc Spray Welding
Spray arc welding is one method of transferring molten material in the form of many small droplets, each with a diameter smaller than the filler wire. The arc is stable and spatter-free because there are no short circuits.
The current and voltage values must be above certain limits for spray arc welding to be successful. As a result, the workpiece receives more heat than with short-arc welding, and only materials with a thickness of 5 mm or greater are suitable for spray-arc welding.
Because of the high heat input, the weld pool is also large, so welding must be done horizontally. It should be noted that using CO2 as the shielding gas does not result in a pure spray arc.
The shielding gas must be pure argon, preferably with a trace of CO2 (no more than 25%) or O2. Spray arc welding is especially well suited for MIG welding of aluminum and stainless steel, where the primary shielding gas is argon.
- Flame spraying Process
Flame spraying, also known as oxy/acetylene combustion spraying, was the first thermal spraying technique developed around 100 years ago. It operates on the same principles as a welding torch, but with the addition of a high-velocity airflow to propel molten particles onto the substrate.
The coating material can be wire or powder. Flame spray coatings are frequently melted after application to improve adhesion and coating density.
- High-Velocity Oxyfuel (HVOF)
The HVOF (High-Velocity Oxy-Fuel) process burns oxygen and a limited number of flammable gases such as propane, propylene, or hydrogen. Although the HVOF system employs the basic combustion principle, the spray gun is not the same as a standard oxy-fuel spray gun.
Higher flame temperatures and velocities are produced by the HVOF gun differences. As a result, the powder is more thoroughly melted, and there is more kinetic energy available to “flatten” the melted coating particles. Superior bond strength and coating density are produced by the HVOF process.
- Plasma spray process
The plasma spray process (non-transferred arc) uses inert gases fed past an electrode to induce the “plasma” state of the gases. A tremendous amount of heat is released when the gases exit the nozzle of the gun apparatus and return to their normal state.
In the plasma “flame,” a powdered coating material is injected and propelled onto the substrate.
- Spraying with Detonation
Detonation spraying is one of many thermal spraying techniques used to apply a protective coating to the material at supersonic velocities to change its surface characteristics. This is done primarily to increase a component’s durability.
- Cold Spray Process
Cold spraying (CS) is a method of coating deposition. Solid powders (1 to 50 micrometers in diameter) are accelerated to 1200 m/s in a supersonic gas jet. Particles deform and adhere to the surface as a result of the impact on the substrate.
The spraying nozzle is scanned along the substrate to achieve uniform thickness. Cold spraying can deposit metals, polymers, ceramics, composite materials, and nanocrystalline powders.
Advantages of Spray Welding
- Spray welding ensures a smooth weld
- It has high penetration and is suitable for metal thicker than 3/16
- It has high weld deposit rates, which increases productivity
- The presence of very little spatter
- Inexpensive: use of less expensive material and strengthen by spray
- Spray welding is versatile, most metals, ceramics, and plastics can be sprayed
- Works in a variety of thicknesses
- Fast processing speed: spray times from 3 to 60 lb/hour (depending on the process used)
Ufumbuzi wa Spray ni Nini? Spray welding inahusu aina mbalimbali ya michakato ya kulehemu ambayo kutumia thermal spraying. Ni mchakato wa viwanda ambapo poda au waya ni atomized na gesi compressed kwa kasi ya juu na kunyunyizia juu ya uso wa chuma. Spray welding hutumia plasma ya viwanda, moto, detonators, arc spray, na high-velocity oxyfuel. Kwa sababu ya joto kubwa zinazozalishwa na spattering kulehemu, taratibu na kanuni lazima kufuata kwa ukali ili kuepuka madhara kwa watu na mazingira. Utaratibu wa Kuunganisha kwa Uswidi ni Nini? Thermal kunyunyizia ni neno pana kwamba inahusu aina mbalimbali ya michakato ya mipako. Utaratibu wote wa kulehemu unahusisha matumizi ya vifaa vya kufunika, kama vile fimbo, poda, au waya, ambayo huyeyushwa na vyanzo mbalimbali vya nishati. Ni mchakato wa kufunika wa viwanda ambao una chanzo cha joto na nyenzo ya kufunika iliyoyeyuka katika matone ambayo huchapwa kwa kasi kubwa. Mtiririko wa atomization au gesi husukuma kunyunyizia kuelekea substrate. Kupiga dawa kwa joto ni mchakato wa matumizi mbalimbali ambao pia unajulikana kuwa na ufanisi mkubwa. Ni inaweza kuwa mbadala bora kwa ajili ya matibabu mbalimbali ya uso, ikiwa ni pamoja na joto au nitride matibabu ya taratibu, chrome, nickel plating, na anodizing, miongoni mwa wengine. Mapendezi ya mtu binafsi huathiri unene wa mipako. Mchoro huo hurudisha sehemu zilizoharibiwa na sehemu za msingi za mashine. Inaweza pia kutumika kuboresha utendaji wa kipengele na uimara. Ikiwa umechukuliwa kwa uangalifu, unaweza kudumu hadi 70% kwa muda mrefu. Arc Spray Welding ni mbinu ya kuunganisha chuma iliyomwagika katika fomu ya matone mengi madogo, kila moja na kipenyo kidogo kuliko waya wa kujaza. Arc ni imara na spatter-free kwa sababu hakuna nyaya fupi. Thamani za sasa na voltage lazima ziwe juu ya mipaka fulani kwa ajili ya spray arc welding kuwa na mafanikio. Kwa sababu hiyo, kipande cha kazi hupokea joto zaidi kuliko kwa kulehemu kwa arc fupi, na vifaa tu vyenye unene wa 5mm au zaidi vinafaa kwa kulehemu kwa arc ya kunyunyizia. Kwa sababu ya pembejeo ya juu ya joto, dimbwi la kulehemu pia ni kubwa, kwa hivyo kulehemu lazima kufanywe kwa usawa. Ni lazima ieleweke kwamba kutumia CO2 kama gesi ya ulinzi haina kusababisha arc safi kunyunyizia. Gesi ya ulinzi lazima iwe argon safi, ikiwezekana na CO2 (si zaidi ya 25%) au O2. Spray arc welding ni hasa vizuri suited kwa MIG welding ya alumini na chuma cha pua, ambapo gesi ya msingi ulinzi ni argon. "Mfano wa ""moto spraying"" ni aina ya moto spraying, ambayo ni pamoja na oksijeni na acetylene, ambayo ni moja ya mbinu ya kwanza ya joto spraying maendeleo karibu miaka 100 iliyopita." Inafanya kazi kwa kanuni sawa na tochi ya kulehemu, lakini kwa kuongeza mtiririko wa hewa wa kasi ili kusukuma chembe ziliziyeyuka kwenye substrate. nyenzo ya mipako inaweza kuwa waya au poda. Flame kunyunyizia mipako ni mara nyingi kuyeyuka baada ya maombi ya kuboresha adhesion na wiani mipako. HVOF (High-Velocity Oxy-Fuel) ni mchakato wa kuwaka oksijeni na idadi ndogo ya gesi zinazoweza kuwaka moto kama vile propane, propylene, au hidrojeni. Ingawa mfumo wa HVOF hutumia kanuni ya msingi ya kuchoma, bunduki ya kunyunyizia sio sawa na bunduki ya kawaida ya kunyunyizia oxy-mafuta. Juu moto joto na kasi ni zinazozalishwa na tofauti HVOF bunduki. Matokeo yake, poda ni zaidi kikamilifu kuyeyuka, na kuna zaidi kinetic nishati inapatikana kwa <unk>flatten<unk> kuyeyuka coating chembechembe. Nguvu ya juu ya uhusiano na wiani wa mipako hutengenezwa na mchakato wa HVOF. - Utaratibu wa kunyunyizia plasma Utaratibu wa kunyunyizia plasma (arc isiyohamishwa) hutumia gesi zisizo na nguvu zinazopelekwa kupitia elektroni ili kusababisha hali ya "plasma" ya gesi. Kiasi kikubwa cha joto hutolewa wakati gesi zinapotoka kwenye mdomo wa kifaa cha bunduki na kurudi katika hali yao ya kawaida. Katika plasma <unk>moto,<unk> poda ya mipako ya nyenzo ni injected na propelled juu ya substrate. Spraying na detonation ni moja ya mbinu nyingi za thermal spraying kutumika kutumia kifuniko kinga kwa nyenzo katika kasi supersonic kubadilisha sifa zake uso. Hii ni kufanyika hasa kuongeza sehemu ya uimara. Cold Spraying (CSS) ni mbinu ya kufunika. Poda ngumu (miani ya 1 hadi 50 micrometers) huongeza kasi hadi 1200 m s katika jet ya gesi ya supersonic. Chembe deform na kushikamana na uso kama matokeo ya athari juu ya substrate. Spraying nozzle ni scanned kando substrate kufikia unene sawa. Kupiga dawa kwa baridi kunaweza kuweka metali, polima, kauri, vifaa vilivyofanyizwa kwa vifaa, na poda za nanocrystalline. Spray welding ni mbinu ya kawaida ya kulehemu, ambayo inahakikisha upanuzi wa chuma na inasaidia kwa chuma cha unene wa 3x16mm, na inahakikisha upanuzi wa chuma na unene wa chuma.