Composite sinks are a plastic resin composite that is much cheaper than granite sinks as well as being much lighter. However, drilling into composite sinks requires different tools and processes than granite because of the different composition. The most important change is the need to avoid excess heat because the resin can, and will, melt if you reach too high of a temperature. This temperature will differ depending upon the brand of composite that you are using.
Lay the sink on two sawhorses as the sink will not sit on a flat surface. Ensure that the sink is sitting stable as the drill will exert significant torque, which could move the sink while you are working on it. Put on safety goggles and a face mask, as the drilling process will throw up a lot of plastic dust.
Tape the approximate location of where you will be placing the faucet. The tape will give you a place to outline the faucet cutout so you know where to drill. The tape will also protect the surface of the composite sink so that your drilling will not inadvertently scrape the sink.
Place the faucet on the tape, using a measuring tape to centre it. Use a pencil to outline where the hoses will poke out of the underside of the sink. Outline the space that the faucet will cover to show you what areas you need to avoid drilling into.
Put a drill bit in the chuck of your power drill or rotary hammer. Place the drill against the centre of the holes that you previously outlined. Pull the trigger midway so that you are only at half throttle and push firmly against the drill. Stop drilling immediately if there is smoke or you smell burning. Take the drill out every 30 seconds to allow the sink to cool; blow away dust. This will make a pilot hole for the circular saw to use.
Place a circular saw, preferably a new one, into the chuck of your power drill. Place the power drill over the hole, aligning with the pilot hole you just drilled. Pull the trigger to half throttle and repeat the drilling process you just did with the pilot hole. Repeat this pilot hole and circular saw drilling process for every hose hole you need to drill. Take the tape off when you are done.