When it comes to efficiency, size does not matter. The following shop equipment-efficiency items are directed to any shop operation, large or small, interested in upgrading these often-overlooked areas so commonly prone to be subtle pockets of inefficiency.
Primary and secondary shearingWith the development and acceptance of automated coil lines, plasma- and laser-using metal processing and cutting technology, there continues to be a basic need in all sheet metal shops for efficient manual shearing.
In the large-volume shops this continues to typically be represented by mechanical shears having a capacity of at least 10 gauge and 10-foot length, a squaring arm with measuring tape on the front, and a manual or power-driven back gauge. A sheet metal shop without an efficient shear would be exactly like a seamstress shop without a sewing machine. That is exactly how basic this need is.
But what about the secondary shearing needed by larger shops? Secondary shearing is the shearing of accessory and specialty items such as pipe saddles, small fittings, or roof flashings, etc., usually from scrap or primary shear drop-off pieces.
And what about the shops smaller in both floor space and volume? Many smaller shops have limited shearing capability with 3-, 4-or 6-foot shears, which is similar to the secondary shearing often found in larger shops.
The secondary shearing in any shop should - and can - be just as efficient as the large shop’s primary shearing. It’s simple to do. Make sure that any shear, large or small, primary or secondary, has a front squaring arm with imbedded tape measure and an efficiently accessible material rack.
Many, if not most, secondary shears in large shops and 3- to 6-foot shears in small shops are without efficient back gauges and have no taped squaring arm on the front.
Invariably, this forces shear operators to alternately tape left and right edges of the piece being sheared, or to even have two workers with two tapes involved. Either situation is an efficiency disaster. There are several fixes for this unacceptable situation.
Order a factory-made taped front squaring arm, if available at a reasonable price.
Contact your local shop equipment dealer and see if they have a used taped squaring arm that could be fitted onto the shear. If so, this may be your most economical fix.
Make a squaring arm for your shear. This can be done relatively inexpensively and quickly. The materials needed are 2-inch by 2-inch by 1/4-inch angle iron, a 6-foot-long piece of 1 1/2- inch by 3/8-inch machine-type bar stock that has sharp, square corners, a piece of 2-inch pipe, a small piece of quarter-inch plate, and a tape from an old measuring tape. There are threaded bolt holes in the bedplate of most shears for attaching a squaring arm.
Shearing areaIt is important to set up an efficient, dedicated shearing area in any shop, large or small. A typical efficient shearing area consists of key components including the shear, the primary material storage device - usually some type of sheet rack - and sometimes a power duct notcher.
The equipment and arrangement shown in the page 32 sketch represent an ideal shearing area setup for any size shop with any size shear. Note the presence of three “eyeball” rollers, which allow a single shear operator to handle heavier sheets safely and efficiently without assistance. The eyeball roller stands are simply industrial eyeball rollers welded to the top ends of 2-inch diameter pipe, placing the top of the rollers at the bedplate level of the shear.
Also notice the “drop gate” installed into the 10-inch-long squaring arm. This is to allow the shear operator to “shortcut” the material drop-off retrieving loop by reducing the footsteps from about 66 feet (around the end of the 10-foot squaring arm) to about 26 feet (through the squaring arm).
The drop gate consists of simply cutting out an 18-inch section of the squaring arm and attaching it back with an industrial precision hinge. This is another simple concept that saves hundreds of footsteps and a lot of time during the shearing process. Also note the open-arm sheet rack described in materials storage.
Materials storageMaterials in an HVAC sheet metal shop include numerous types, each requiring its own individual storage device, efficient access to and from that storage device and efficient positioning of the device relative to the “work cell” area that it supplies.
Collectively, these three are technically referred to as affinity positioning. Unfortunately, sheet metal shop equipment affinity positioning is almost never established by design and logic but is invariably established over long periods of time as additional shop machines are acquired. This usually results in inefficient material storage and handling which can add unacceptable lost motion labor costs to critical work processes and flow.
Let’s take a look at these HVAC material storage devices and areas and establish some basic affinity positioning for maximum efficiency.
Sheet stockSheets are stocked in various lengths, widths, and metal types, the most common being galvanized for ductwork fabrication. These sheets represent the most accessed and handled material in the shop and therefore hold great potential for efficiency improvement and labor savings without an extraordinary investment of capital or time.
Common and incredibly inefficient material handling processes include hand-carrying 20-foot lengths of angle iron and flat sheets down two flights of stairs after curbside delivery and placement of flat sheets underneath layout benches located far from the power shear. Interestingly these situations seem to exist more frequently in the smaller volume shops, perhaps because of the belief that since they don’t do as much volume as the big shops it’s not costing much to be inefficient.
This philosophy is wrong and costly. There is no logical reason to do anything inefficiently by design or oversight in any shop, large or small. A dollar in labor savings is just as important in a small shop as it is in a big shop.
The most efficient way to off-load and store sheet stock is by forklift from the delivery truck into an open-arm sheet rack. Most shops, large or small, have access to some type of forklift or can purchase a small forklift for a few dollars. Having the forklift is usually not the problem. The problem is having the open-arm sheet rack, access to it, and an efficient positioning of the rack to the sheet processing equipment.
Open-arm sheet racks are standard fare in almost any other industry and are readily available.
Be sure to contact the manufacturer’s sales engineering people and let them put together the appropriate components and pricing based on the following criteria:
• Storage for up to 60- by 120-inch skidded sheets (requires 60-foot-long arms)
•Weight capacity of 5,000 pounds at each level (about three vertical inches thick of metal plus the four-by-four skids)
• Adjustable distance between arms to be assembled in shop at 12 to 15 inches of vertical spacing between arms. This is plenty of room for forklift loading.
Height of uprights can be up to 20 feet but most shops use 8 feet.
Eight-foot-high uprights will accommodate five levels of skidded sheet bundles.
These five levels usually represent the most commonly used gauges: 26, 24, 22, 20 and 18.
This configuration using 8-foot-high uprights provides four storage levels at four sets of arms in addition to a fifth storage level on the upright’s floor bases.
Angle iron and bar stockAngle and bar stock materials are sometimes snaked or dragged by forklift off of the delivery truck and onto the receiving dock, where the pile may remain until used. This is potentially disastrous to both efficiency and personal safety, since workers must step over the pile day after day. Common causes that spawn this bad situation include simply not having a forklift-loadable open-arm angle iron rack or not having a rack positioned properly for loading.
See the sketch for an ideal arraignment for quickly and efficiently off-loading long-stock materials directly into an open-arm angle rack. Many sheet rack vendors also provide angle/bar stock racks.
Duct liner insulationDuct liner insulation is held in storage to serve three areas of shop operations:
First, the liner rolls are stored in the insulating area for duct fittings where they are loaded as needed onto a roll holder attached to the end of a manual liner-cutting table. The profile of an efficient liner storage platform shown in the sketch.
Second, this same type of overhead duct liner storage platform is commonly used over the insulating section of automated coil lines. This is particularly efficient as the larger rolls of duct liner used on coil lines would require two persons to lift and load them onto the roll holder of the coil line.
Third, the overhead duct liner storage platform is becoming more commonly used to accommodate the highly efficient automated liner-cutting tables that use plasma fitting cutting software data in conjunction with the new “smart knife” technology to more efficiently and accurately cut matching liner pieces for the metal fitting patterns. This is a prime example of the longstanding syndrome of relative inefficiency, sometimes referred to as inefficiency balance, between stages of a shop process.
Slip-and-drive connector stockOne of the most common examples of false economy in shops, especially the smaller-volume ones, is their dependability and expected cost savings of cutting up drop-off metal to make slips and drives.
The problem with this idea lies in three areas. First, there is no guarantee that there will be enough drop-off metal at any given time to produce the required amount of slips and drives. Second, there is no guarantee that the correct gauges will be either available or selected from the pile of drop-off metal. Third, the only option remaining when either of the first two fall short is to use new prime lock-forming sheets which costs almost as much as the formed slip-and-drive stock from the providers, who do not have to use lock-forming quality metal for connectors.
The most efficient approach to slip-and-drive profitability is to purchase and inventory an adequate amount of 10-foot-long connector stock but have a lower-paid worker shear and form supplemental quantities only when the proper amounts and gauges of shear drop-off are available and even then only when there is absolutely no duct fabrication work in progress.
The bottom line is that shop equipment efficiency and productivity is totally dependant on efficient material handling into and away from the equipment.
With a sheet storage rack properly positioned and a taped squaring arm, a $30,000 power shear may cut 10 blanks a minute, but without a properly positioned material rack or taped squaring arm that same expensive piece of shop equipment may as well be a foot-operated “stomp” shear cutting two blanks a minute.
Considering the average HVAC sheet metal shop profit margin is around 10 percent, there is simply no room to have expensive, potentially efficient shop equipment restrained by inefficient support systems.
For reprints of this article, contact Jill DeVries at (248) 244-1726 or e-mail firstname.lastname@example.org. Contact Jim Segroves at email@example.com.