People often assume that using a milking machine would be more work that milking by hand because of the time to clean the machine. Actually its surprisingly quick to clean after milking. And it only occasionally needs a more thorough clean. Much of the information you find online about cleaning milking machines refers to large scale dairies that are milking a hundred or more cows a day. If you are only milking one or two cows you can use a simpler and quicker process, and gentler chemicals, to keep your machine clean.
The only extra-large gloves at the supermarket were pink...
After every milking, as soon as possible, we tip out the milk (either for calves or for our consumption) and clean the milking machine. The first step is a bucket of warm soapy water (not too hot, as steam can damage the vacuum pump, and hot water can actually make the milk solids more difficult to remove), which gets sucked through the milking cups and through the machine. We use a few drops of dishwashing detergent in the water. We then slosh this around inside the milk can and wipe off all the hoses before tipping out the soapy water. The next step is a rinse with a bucket of warm water (also sucked through the milking cups). Finally we leave the milk can upside-down to drain. This is all that is necessary after twice daily milking and takes only about 10 minutes. If the milking machine is cleaned immediately after the milk is tipped out, this amount of cleaning is sufficient. When the milking machine is left unwashed for longer periods (even an hour or so, if other farm chores demand attention), minerals, fat and protein from the milk will gradually form deposits called "milk stone" inside the milking machine .
About once a week, or if we haven't used the machine for a while, we give it a more thorough clean with additional chemicals to remove milk stone deposits. It is generally recommended to use a caustic or a caustic/chlorine detergent. You can buy specialty chemicals from a dairy supplier, but you can usually also find something suitable in the supermarket cleaning isle. Look for a cleaner that contains Sodium Hypochlorite and Sodium Hydroxide (with minimum fragrance as you don't want your milk to taste lemon-fresh). Both of these are strong chemicals that can damage your skin and eyes, so make sure you wear gloves and glasses while cleaning your milking machine with these chemicals.
Acid milk stone remover (based on phosphoric or nitric acid) can also be used (for example). This would need to be purchased from a dairy supplier. Acid cleaners are better for hard water, which tends to react with caustic cleaners and reduce their effectiveness. Again, this is a strong chemical and care should be taken to avoid contact with skin and eyes. You can read all about the chemistry of different cleaners here. Never combine ammonia with acid or chlorine cleaners, as you will cause a chemical reaction, if in doubt, its best to just use one cleaner at a time.
When we do the big clean, we usually also take the opportunity to pull off all the hoses and give them a clean with a bottle brush. We have bought a range of sizes of bottle brush, and one small one is particularly useful for cleaning the long tube between the milking machine claw and the milk can, we tie it on a piece of bailing twine and pull it through the tube a few times (hot tip from Pete, the best way to get the twine all the way down the tube is running water or compressed air). When you first get your milking machine, its a good idea to take it apart to find out which bits you can get into the clean properly.
The queue at milking time
Do you use a milking machine? How do you clean it?