Industrial Sewing Machines for Home Use
Heavy Duty is the correct phrase for industrial sewing machines made for home use. These machines are not commercial grade by any means, but do have increased speed capabilities up to 1100 stitches per minute and the added frame strength to support that speed. A machine in this category can handle thick layers such as a quilt and heavier fabrics like upholstery and denim.
One thing to remember when using industrial sewing machines is to always use high quality thread. Cheaper thread is guaranteed to snap under the boosted speed and blame tends to be focused on the machine rather than user error. In addition to quality, thread needs to be the correct weight to match the type of material being used.
The right sized needle for the task at hand is also crucial for problem-free sewing. Trying to force a ball point needle through several layers of denim for instance is just asking for trouble. The needle will break and tear up the fabric through no fault of the machine. It's important to do this research before starting a new project and it will serve to make you a more knowledgeable sewist overall.
Before making a purchase for a heavy duty sewing machine, peruse through user reviews which contain valuable feedback from others' trial and error. All machines, even the best ones have little idiosyncrasies that often show up in reviews and knowing about them up front will save time and frustration. For example, in an Amazon review for the Singer 4411 Heavy Duty model, a user expressed that by holding the ends of the thread up when starting a seam will avoid thread tangling - an excellent tip!
Even with all the usual features of lighter weight machines, home industrial sewing machines are generally used for high speed straight and zig-zag sewing. Their heavy duty capability is what sets them apart from rest of the general purpose sewing machines.