common questions

Q: There seems to be virtually no limit in the type of powder that can be sprayed with the Detonation Gun System. What typical powder mesh size is used?

A: The practical range is 10-100 microns. However smaller or larger ranges are also possible if needed.

 

Q. Does it require anything special with regard to powder cut? No

 

Q. What type of powder feeder is used ?

A: It is compatible with all standard powder feeders (Metco or Miller thermal for example) and we recommend using a standard feeder. The gun comes supplied with our feeder. Several powder feeders can be connected at the same time.

 

Q. What are typical:

a. spray distances - Typical spray distances are: 60- 120 mm ,

b. spray rates -

Detonation Gun spray rates are similar to HVOF. The deposition rate will depend on detonation frequency (10 - 55 shots per second), and powder loading speed. On average it is the same as for HVOF systems, and in some cases can be made higher. Process optimization must be done, to ensure the stability of coatings at high rates and at a high coefficient of powder use.

 

Q. What are the maximum spray rates and deposit efficiencies for: 88/12 Wc, 75/25 CrC/NiCr, Inconel 625 for example ?

A: In this example, the maximum spray rates are: 0.3-0.4 lb/min and deposit efficiency is 80%, for an optimized process.

 

Q. What gases are used and what are the consumption rates?

A: All of the typical gasses may be used; however, economy, and low temperatures, can best be achieved when using propane, methane, or natural gas, which you may already have in your plant. Gas consumption is 1/3rd to 1/10th the consumption of HVOF, depending on whose system is being compared. Please also remember that we do not use Nitrogen, which affects the quality of the coating.

The Detonation Gun process is intermittent. It burns much less gas, for a given powder mass. The typical flow rates in the Detonation Gun (25 to 60 ft3 per minute) are about 5-10 times less than in an HVOF system. Every minute, you save quite a lot in gas cost, vs the continuous HVOF process.

Gas pressures are much lower in the Detonation Gun process, than in HVOF: 70 to 210 kPa for the Detonation Gun vs 700 - 1000 kPa for the HVOF process. As a result the Detonation Gun can use a regular low cost gas supply system, with standard hoses (including natural gas). The HVOF process requires high-pressure hoses, and a high-pressure source of gas.

 

Q. You mentioned no moving parts, are there any spares consumed during normal operation ?

A: No! Detonation Guns have been known to spray for 10 years without any replacement of major parts.

 

Q: I have a very expensive part to spray. Is there any chance for spitting of copper, or tungsten, on my part?

A: No! Detonation Guns do not have nozzles, so it is not possible for the spitting of copper or tungsten to occur.

Q: What type of cooling, and how much cooling water is required ?

A: About 1 gpm - tap water only, no chiller, heat exchanger, or booster pump is needed, and this cooling water may be recirculated, from a tank, to conserve water consumption.

 

Q: What is the electrical energy consumption?

A: The Detonation Gun consumes about 100 Watts of power, or about 1000 times less than plasma. There is also an additional saving, when compared to HVOF consumption, as HVOF also uses special heat exchangers to cool the water.

 

Q: Is it possible to maintain substrate surface temperatures below 100 0 C for all processes?

A: Yes, the temperature of the substrate during the Detonation Gun process can be maintained below 100 C . It can be held to room temperature, if needed. This will require additional substrate cooling by direct or indirect method (for example blowing cold gas). For continuous processes like HVOF or plasma it is generally impossible to keep the temperature below 100 C in the production environment.

 

Q: Does the material being sprayed make any significant difference to the substrate temperature?

A: The material sprayed does not have large effect on the temperature of the substrate.

 

Q: Does the selection of gases make any significant difference to the substrate temperature?

A: With the Detonation Gun process, the selection of gases does make a difference in the temperature. Acetylene and hydrogen result in higher temperatures than propane, for example.

 

Q: What kind of rep-rate does the Detonation Gun have?

A: The normal rep rate (explosion frequency), for a production gun, is typically 6-8 shots per second; however, with our design, high frequencies are possible and have been demonstrated at 55 shots per second. At such high frequencies, however, special process development must be done to ensure process integrity.

 

Q. What is the noise level during spraying ?

A: 140 db at the gun, but this is intermittent, and easier to control than continuous HVOF.

 

 

 

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