Do you operate a small sheet metal shop or HVAC company?
Snips magazine published an article in April 2007 discussing operational guidelines and purchasing advice for small sheet metal shops and HVAC companies. The article also lists the 21 equipment choices for shops making up to 60,000 pounds of ductwork a year. We also did one up! Check it out HERE.
Virtually all heating and air-conditioning companies need HVAC ductwork and other sheet metal items made fast. Most need small-quantity sheet metal orders fabricated quickly and efficiently. Why is efficiency so important on small orders? Efficiency is especially important on those quick, small orders because they are inevitably generated by unexpected job site situations.
Emergency unit change-outs or structural conflicts mean there often isn’t any money in estimates for ductwork changes. When setting up a small shop on a budget, you must be efficient. There is no excuse, nor is there any logic, in intentionally setting up a shop to fabricate quick, small-order jobs inefficiently when, by their very nature, they offer so little profit potential. This applies to shops of all sizes.
This assembly table incorporates several important attributes unique to its design. Note the two layers of 3/4-inch plywood that envelope the roofing felt, which creates a sound-dampening effect when assembling ductwork. This is especially important when closing Pittsburgh seams on unlined duct using an air hammer. Additionally, the table is low enough to provide a comfortable working height to assemble average-depth ductwork. The plywood working surface provides less slippage of the sheet metal parts when being tacked up. Also note the adjacent miscellaneous storage bins, which minimize footsteps. Sketch by Jim Segroves.
Here are some basic operational guidelines, followed by some equipment selection guidelines that will be very beneficial to setting up or improving a small sheet metal shop in a low-volume HVAC company.
Set up the operation to be as efficient as possible in procedure, equipment, and flow.
One man, one job. Never use two or more people at a workstation when one person can do the process. (Note the “one worker, one job” concept in the selection of shop equipment.)
Set up turnaround time guidelines for installers to adopt. A good rule is to have them submit the job by noon today to expect it to be ready for delivery by noon tomorrow. In other words, establish a 24-hour minimum guideline. There are always exceptions that require less time, but the goal is to make those emergency orders rare rather than common. The key to this largely lies in educating both the installers and the customers in this concept.
Make fax machines available in the lead installers’ trucks so that they can instantly submit new quick-turnaround orders throughout the workday rather than waiting until they return to the shop that evening or the next morning.
Take phone and fax orders in a quiet area to enhance communication and concentration. Prepare each job for fabrication in that area or preferably a closed-in shop office.
Convert the ordered items to shear lists for duct and fitting parts, vane and runner cut lists, and connector lists. This can be done manually but is best done by a computer. These lists are automatically generated by plasma-cutting software if such a table is used.
Use the new Duct Construction Standards book from the Sheet Metal and Air Conditioning Contractors’ National Association to create a simplified set of pressure-class tables that incorporate your shop’s technology. If you do not have plasma software to provide seams, gauges and connector data automatically, it must be done manually for each piece of duct being made. This can be very time consuming and error-prone. Condense the SMACNA tables to your shop’s standards for quick and accurate reference.
Arrange your facilities to discourage non-shop employees or customers from being in work areas. They can hinder productivity and create unsafe situations for both the visitor and the shop worker. Put signs on the outside of shipping doors and personnel entrance doors that say: “No admittance,” “Employees only” or “Please use other door.”
Be aggressive in tracking shop-burden costs for the first year. This includes all costs that are incurred in the daily operation of the shop, not including direct labor or direct materials, since those items appear in estimates. Examples include energy costs, indirect labor, equipment purchase and repair costs, supplies, utility costs, building rental or payment costs, etc.
Accurately tracking the first-year costs is important because those costs will be used to cover shop-burden – overhead – costs in estimates the second year. Shop-burden cost numbers for estimating fabrication expenses are always based on the previous year’s figures and are a percentage of the previous year’s direct labor and material costs.
Do not hesitate to leverage the advantage of buying duct for larger jobs from a dedicated duct manufacturer. Large suppliers can be very competitive when comparing costs for a smaller, less automated shop.
It can be very advantageous for new businesses to buy a complete small, manual shop. Trade magazine classified advertising sections are a good place to begin. They’re also a good place to run an ad asking to purchase such a shop.
Existing shop equipment and inventory can often be purchased for as little as 60 percent of market value. However, should you consider the purchase of an established shop’s equipment, be sure to compare that equipment with the recommended shop equipment list and consider replacement costs of any less efficient equipment that would be included in the buyout.
Buy shop equipment that is designed with the “one worker, one job” concept in mind. The use of two workers on a piece of shop equipment usually doubles the labor cost.
Consider contacting reputable used sheet metal equipment dealers, both local and regional. Used shop equipment usually sells for 30 percent to 40 percent less than new equipment after being refurbished to factory specifications. There are some great deals out there.
Set up your start-up shop to allow for growth and upgraded or additional equipment.
Allow as many doors as necessary for good ventilation in warm weather. Shop productivity is directly related to ambient temperature and humidity. Productivity can be even higher in air-conditioned shops.
Base your shop equipment and receiving/shipping doors on handling 10-foot-long materials. Also, plan for receiving those sheets on forklift skids that will be about 11 feet long. Your receiving doors will need to be a minimum of 12 feet wide and your shop equipment should be able to accommodate 10-foot-long sheets.
Plan on using mostly 5-foot-wide sheets. The sheet metal industry is slowly moving toward the use of 6-foot-wide stock, but that is many years in the future, if at all. There’s a lot of 4-foot-wide equipment out there at bargain prices, but it really is not a bargain. Five-foot-wide by 10-foot-long stock should be your base.
This does not represent some smaller shop tools needed but provides a good overview for budgeting purposes. Be sure to provide ample lighting and ventilation, and to provide a simple aisle way to ensure efficient workflow as you grow.
Using these recommendations will ensure that your start-up or existing smaller volume shop will be as efficient and competitive as any, and better than many.
For reprints of this article, contact Jill DeVries at (248) 244-1726 or e-mail firstname.lastname@example.org.
This sketch of a 2,700-square-foot shop incorporates several important equipment upgrades to allow it to handle 400,000 pounds of ductwork a year. The upgrades can be done quickly or over several years. They include: replacing a manual layout table with a plasma machine, adding a 10- by 16-foot notcher for straight ducts, replacing a 10-foot medium-duty hand brake with a 10- by 12-gauge hydraulic rotating die-type power brake, adding a table-model power-drive turner and adding an automated pin spotter. Sketch by Jim Segroves.
Sidebar: 21 equipment choices for shops making up to 60,000 pounds of ductwork a year
Duct/fitting layout table
These magnetic tables have been available for over 50 years and will serve your manual start-up shop quite well until your growth can justify a plasma cutting machine. These tables incorporate two magnets to hold the sheet in place, two rolling shears for both the 5-foot sheet end and for the 10-foot sheet length, and a 10-foot-long notcher attached to the operator end.
This is a very efficient layout, cutting, notching unit for small operations. The table also has sheet storage racks built in underneath. However, do not store the sheets, particularly the 5-foot-wide sheets, underneath, as the stocking and removal of the sheets is extremely inefficient (see open arm sheet storage rack in No. 2). Also, note that the space allocation on the shop floor plan sketch allows ample room for the future change of this manual table to a plasma cutting table.
Open-arm sheet storage rack
These standard open-arm sheet storage racks are commonly used and are available new and used. You will need a five-tier rack including the floor level. This will hold the five standard gauges – 26, 24, 22, 20 and 18. The uprights will be 8- or 10-feet high and the arms can be set up at 3-inch increments, providing 15-inch clearance at each level. Such clearance will allow room for about 3 inches of sheet plus 4-by-4-foot oak skids, leaving room for the forklifts. Ideally, these racks are loaded by forklift; however, they can also be loaded by hand if necessary.
The sheets can be removed from the side or from the ends. Note that the fitting-cutting table and the 10-foot shear are positioned to offload the 5- by 10-foot sheets directly onto those pieces of equipment. This is a basic efficiency concept necessary for any size shop. Each set of arms should hold 5,000 pounds.
Snap-lock roll forming machine
This machine will be your primary longitudinal seam former for the majority of your ductwork and fittings. It is a very important machine. It should:
- Form male and female snap-lock edges.
- Run at 60 to 65 feet per minute.
- Handle 20- through 26-gauge capacity.
Light-gauge Pittsburgh machine
This machine will serve the lighter gauges for the female Pittsburgh. It should:
- Form small female Pittsburgh seams on light-gauge metal.
- Runs short pieces for ell throats, etc.
- Handle 20- through 26-gauge material.
- Run at 75 feet per minute.
Auto-guide attachment for light-gauge Pittsburgh machine
This attachment is for turning male Pittsburgh edges on curved fittings.
Pittsburgh machine with “3-1” rolls. This machine is for running Pittsburgh seams on heavier metal. On the opposite side, it will be set up with 3-1 rolls. The 3-1 rolls are necessary to efficiently roll-form taps in edges, flanges for standing seams and female standing seams. It should handle:
- 18- through 26-gauge capacity.
- Run at 40 to 45 feet per minute.
- Have an outboard 3-1 roll-form tap-ins, standing seam male/female flanges.
Workbench. It should be:
- 12-feet long by 5- to 6-feet wide. (This 12-foot length provides room for workers’ tools at the end.
- Have a 30-inch working height.
- Topped with 2- by 12-inch boards covered with quarter-inch Masonite work surface.
- 10-foot long straight edge along worker’s side.
Ten-foot power shear
This is a primary piece of equipment for any shop. For a small start-up shop, the shear should have the 10-foot-long cutting capacity, handle at least 18- or 16- gauge metal, and by air- or electric-powered. It should also:
- Handle a minimum of 30 strokes per minute.
- Have a front-operated back gauge.
- Have a 5- or 10-foot squaring arm on front.
This can be a manual drive cleat turner if the budget dictates. However, a table-style, powered, one-worker design should be purchased as volume increases.
Ten-foot bending capacity medium-duty hand brake
The gauge capacity should be no heavier than 16, as the heavier gauge 10-foot brakes are too slow and heavy to use on lighter gauges. The real need is for the 10-foot-long capacity, not heavy-metal capacity.
Light-duty hand brake
An 8- by 18-gauge hand brake is quick and efficient for forming the light-gauge ductwork normally associated with a small-volume shop.
A 5-foot beading machine
A power beading machine is several times faster than hand cross breaking on the brake. It should handle:
- 5-foot-wide material.
- 16-gauge material.
This is necessary for joining metal parts. It is infinitely more efficient than pop rivets. It needs:
- 15 watts minimum.
- 18-foot or longer arm length.
- Automatic timing.
- Air operation.
- Water cooling.
These rolls can be light-duty, manual or powered.
- 3-, 4-, or 5-foot width.
- Minimum 20-gauge capacity.
Duct liner cutting table
These duct liner cutting devices utilize a “pizza” roll cutter on a sliding bar for the cross-cut and usually hold two rolls of duct liner that can be a 1/2 or 1-inch thick. They should be attached to a workbench, similar to item No. 7. It should have:
- A 5-foot wide cutting length.
- A two-roll holding rack.
Duct liner glue spray gun
Most any spray gun of reasonable quality will work. The size and operating pressure data are available from the glue manufacturer. If chemical-based glue is used it must be non-flammable when wet and have a 3,000-cfm exhaust hood.
Duct liner pinning setup
For budget purposes, a manual pinning setup will work reasonably well. Some prefer a hardened backup plate (with grooves to recess the beads from the beading machine) and a magnetic handheld hammer and nail apron. These items are available new and used. An experienced worker can get very fast with this setup.
This is an important but often underestimated item. No one should assemble ductwork on the floor or on 30-inch-high workbenches. Assembly is a big part of duct fabrication and the assembly operation should include the sound-absorbing design and other attributes reflected in the sketch with this article. The table should be served with both air and electricity dropped from overhead (see sketch).
Pittsburgh air hammer
This is required for efficiently closing Pittsburgh seams. It should be:
- Have the air hose at the top – not side – for better balance.
- 16-gauge capacity.
Wire welder with welding bench
An inexpensive wire welder will be adequate to do small welding jobs and to serve the important function of attaching every other vane to the runners when fabricating purchased hollow air-turning vane sets.
Vane-and-connector holding rack and workbench
Vanes and connectors should be purchased, not shop-made. This is much more cost-effective for start-up shops. The vanes and connector workstation table have a standing “S” cutter to efficiently cut the connectors to length in the shop.