Taking care of drilling hammers can help take care of the bottom line.
By LaTisha Shipman
Hammers are not that much different than any other type of piston-operated machinery in that they require oil to maintain performance.
I know you wouldn’t run your truck or rig without oil. We wouldn’t consider doing that because we know failure would be both imminent and catastrophic. But it is also the same with hammers.
One of the most common types of hammers and bits failure is due to a lack of proper oiling. So, consider both the quantity of oil you’re using and the quality of oil you’re using.
Yes, hammers are a consumable, but I want you to get the most life out of your hammer you possibly can. They are an asset worth taking care of. The longer they last for you, and the more footage you can get out of them directly, affects your bottom line. With a little bit of love and TLC, your hammers can go a long way.
Know Your Number
A good rule of thumb for any size hammer is to use two-tenths (0.2) of a quart of rock drill oil per hour per 100 CFM—double that amount if using foam or water injection. Using this formula, a standard 6-inch hammer would need approximately two to three quarts of rock drill oil per hour, depending of course on the CFM.
An inline oiler helps to ensure continual and proper lubrication, though I have seen homemade lubricators serve the same purpose. It is vital you know how much oil you’re consuming, whether you are keeping up with oil consumption using an inline oiler, a homemade oiler, or a red Solo cup.
Please know you will be asked these questions in the event of a hammer or bit failure if submitted for warranty: How much oil did you put in your oiler this morning and did you refill it at any time during the day?
We need to quantify how much oil a red Solo cup or a Gatorade bottle holds and how often you are pouring that down the drill stem. Do you use one Solo cup of oil per drill stem or is it every other? We need to do the math to see if that is enough oil to properly lubricate the hammer.
I challenge you to determine how much oil you are truly using. Keep tabs on it for one day and then compare it to how much oil you should be using. If needed, make the necessary adjustments and then see if your hammer performs better when properly lubricated. Put it to the test.
And if you are running an inline oiler, ensure that it is working properly. We had a hammer come in recently where the piston was seized, and we were able to determine after talking with the customer that the lubricator was not working and had to be replaced.
Lubrication Is Key
Hammers often come in for service to us severely under-lubricated, which causes premature failure of both the hammer and the bit. Rock drill oil helps cool the metal as it lubricates, thus protecting against high heat and localized friction taking place at the point of contact.
Temperature flashes of up to 1400 degrees have been recorded down the hole with under-lubricated hammers. If you have ever seen blue spots on your piston, that’s indicative of those heat flashes and it is not a matter of if but when that piston will fail. And, unfortunately, that is not repairable.
Properly lubricating your hammer also helps protect against corrosion and pitting. Corrosion will always be present where metal, air, and water come together, so with drilling applications we have created the perfect storm. We’ve also added more corrosive agents such as drill foam, potash, and other drilling additives.
The best way to combat corrosion is to lubricate properly, which creates a protective seal around each individual hammer part. Also rinse your hammer clean of foam and additives at the end of each day and blow a mixture of air and oil through your hammer to properly lubricate all internal parts.
Your hammer should be so well lubricated that you see evidence of oil on the bit face.
There are certain types of bit failures that can be directly attributed to a lack of lubrication. Breakages that occur across the shank are generally due to a lack of lubrication. So now, not only are we shortening the life of our hammer by not lubricating, we’re shortening the life of our bits as well.
And in the end, it is the driller hemorrhaging money as he or she keeps replacing bits unnecessarily. Purchasing oil is much cheaper than purchasing bits. Oiling the hammer is the most important and most likely the least expensive maintenance item on your rig.
Consider buying oil in bulk containers such as 55-gallon drums as you’ll often get a price break and have a good supply on hand as you increase your oil usage.
Another important aspect of oiling your hammer is the quality of oil you’re using. “What do you mean?” you ask. “Won’t just any oil work?” Actually, no.
Rock drill oil is specifically formulated with emulsifying and viscosity additives that are needed for high pressure air drilling. If you are in colder climates, you might also need to change your oil out between summer and winter months. There are antifreeze-type additives added to the heavier winter oils.
I recommend the Matex brand of rock drill oil for water well drilling as it is an environmentally safe vegetable-based oil that will not contaminate the well or the aquifer.
Yes, hammers are a consumable, but I want you to get the most life out of your hammer you possibly can. They are an asset worth taking care of.
In addition to oiling your hammer, you also need to apply thread compound liberally to the top sub and driver sub threads as well as to the driver sub and bit splines. This will help to prevent galling.
Copper thread grease is common, but Matex also manufactures an environmentally safe vegetable-based thread compound that does not contain copper. It is another good product designed with water well drillers in mind.
When drilling is finished for the day, blow the hammer out with clean air and oil to properly lubricate all internal parts. If you leave the hammer in the hole overnight, at least raise the hammer above the water level—do not leave the hammer submerged or you might be surprised to find that the piston has seized.
When storing the hammer short-term—three weeks or less—blow air and oil through the hammer and store it horizontally in a dry, temperature-controlled location with both ends covered.
Covering both ends of the hammer will ensure that small critters do not decide to take up residence inside your hammer. If you don’t, there might be a surprise for you the next time you go to put a bit on when you put the hammer back into operation.
We consider it long-term storage whenever you will not be using the hammer for three weeks or longer. An example of this is shutting down for the winter. When this happens, disassemble the hammer completely, wipe the hammer parts down, coat them with oil, and then store the parts either assembled or disassembled in a dry, temperature-controlled location.
The reason for storing the hammer in a dry, temperature-controlled location is to prevent condensation inside the hammer, which would cause corrosion.
You should inspect your hammer every 100 hours. One of the things you should look for prior to cleaning any internal hammer parts is evidence of oil—each part should have a film of oil on it but should not be dripping.
Once you’ve looked over the parts for evidence of oil, clean the parts and inspect closely for corrosion, cracks, pitting, blue heat spots. Remove any small spots of rust or corrosion with an emery cloth or file.
You can polish out shallow surface pitting, but make sure not to exceed your hammer’s wear limits.
As the hammer ages, the hammer’s ability to hold pressure decreases, and that of course affects penetration rates. Failing to hold pressure is indicative of worn internal parts. You may be able to replace items such as the piston and cylinder to extend the life of the hammer, but it’s important to check the wear limits on the internal parts during inspection.
It is up to you to determine when the acceptable time is to shelve the hammer due to loss of performance. And finally, consider keeping your most recent hammer as a backup just in case of downtime with a new hammer. After all, slow drilling is better than no drilling.
LaTisha Shipman is the Texas branch manager for Drilling Equipment Resources. She has more than 20 years of experience in the drilling
industry, with most of that time spent working in manufacturing with DTH hammers and bits. She can be reached at firstname.lastname@example.org.