Roll forming is a metal working process used to form metal sheets into curved or angled structural profiles. A roll forming machine progressively forms metal coils into the desired cross-section by passing it through consecutive sets of rolls. Each set incrementally bends the sheet to the desired shape. Roll forming is an efficient and cost-effective way to manufacture metal roofing panels, siding, rain gutters, door frames, railings, highway guard rails, racks, and many other products.
Compared to other manufacturing processes like stamping or extrusion, roll forming has some key advantages:
- It can create complex cross-sectional profiles using the same initial flat strip or coil of sheet metal. Extrusions are limited to uniform cross-sections.
- There is less waste since the roll formed part can utilize almost the entire width of the raw material.
- Roll forming lines have a smaller footprint compared to stamping presses.
- Rolls are easier to change for quick product changeovers. Stamping dies take longer to swap out.
- Labor costs are lower because the automated process requires minimal operator intervention.
- The forces required to bend the material are spread sequentially over many roll stations, allowing roll forming of high strength steels and avoiding thickness crowning issues seen in stamping.
How Roll Forming Machines Work
A roofing roll forming machine takes a continuous flat strip of metal coil as input and outputs a continuously formed panel or profile as output. The process involves unwinding the coil, feeding it through a series of roll stations to shape the profile, cutting it to length, and recoiling or shearing off panels.
Uncoiling
The raw coil of sheet metal is loaded onto an uncoiler which allows the strip to unwind freely without backlash as it feeds into the roll former. The uncoiler includes a de-coiler brake to provide tension control of the strip.
Feeding
The sheet then passes through a straightener to remove any coil curvature from being wrapped in a roll. It then goes through a feeder with pinch rollers or caterpillar drives that pull the strip through the roll stations at a constant speed. Servo motors on the feeder control the speed and provide precision feeding.
Rolling
The core of the roll forming machine is the rolling mill section. Here the strip passes through a series of roll stations, each with an upper and lower set of rolls. The rolls have matching contours that progressively bend the strip to the desired profile. Typical roll forming lines have between 3 and 20 rolling stations.
Some key roll forming mill components:
- Rolls – Usually made from induction hardened steel. The roll contours match the part profile.
- Roll housings – Adjustable housings to provide precision adjustment of the roll gap spacing.
- Roll shafts – Transmit rotary power from motors to turn the rolls.
- Guide rolls – Additional rolls between stations to maintain strip alignment.
- Support roll stands – Rigid frames that support the roll housings and provide adjustment.
The rolling stations are aligned precisely to prevent twisting or distortion of the strip. The gradual bending staged over many rolls allows complex shapes to be formed without over-stressing the material.
Cutoff
After rolling, the continuously formed strip exits the last station and can be cut to length by a flying shear or cut-to-length shear. A flying shear makes the cut while the strip is still in motion. Static shears cut the stopped strip. The cutoff pieces then go to additional finishing or downstream processes. For continuous products like roofing panels or gutters, the line may recoil the product instead of cutting it.
Key Components of a Roofing Roll Former
Roll forming lines can be built with different configurations to make various roofing products. But in general, roofing roll formers include these main functional components:
- Coil handling equipment – Uncoiler, de-coiler, straightener
- Feeding system – Servo motor drives, caterpillar or pinch roller feeder
- Rolling mill – Roll housings, rolls, roll shafts, support bases
- Cut off – Flying shear or stop-cutoff shear
- Conveyors – Transfer and switch conveyors to move panels
- Runout tables – Supports product after forming
- Controls – PLC and HMI controls sequencing and monitoring
- Safety guarding – Guards, gates, barriers for operator safety
Additional secondary processes may be integrated into the line depending on if offline or further processing is required. These can include:
- Embossing – Texturing rollers to emboss wood grain patterns
- ** Punching** – Punch presses to punch holes for fasteners
- Welding – Longitudinal seam welding for panel joining
- Corrugating – Making transverse bends for decking
- Curing – Heating systems for painted/coated materials
- Cutting – Cross-cut saws, drills for additional cuts
- Marking – Inkjet or labeling for product identification
- Stacking – Automatic stackers to neatly stack finished product
By combining different modular stations and components, roll formers can be flexibly configured for making various roofing product profiles.
Major Types of Roofing Products Made by Roll Forming
Roll forming is ideal for manufacturing metal roofing products because of its ability to form repetitive panel profiles with complex shapes. Here are some of the most common metal roofing components made on roll forming machines:
Metal Roofing Panels
These are the basic metal sheets installed as roof covering. Roll formed panels come in two main types:
- Standing seam – Has vertical ribs between panels. Allows thermal expansion.
- Through-fastened – Uses exposed fasteners through the panels. More economical.
Common panel materials include steel, aluminum, copper, and zinc. These can be bare, painted, or coated with granular or metallic coatings.
Rain Carrying Products
These include:
- Metal Shingles – Formed to look like asphalt shingles with edge profiles.
- Half-Round Gutters – Continuous troughs installed at roof edges. Formed with a curved profile.
- Gutter Covers – Prevents leaf buildup in gutters. Made from perforated rolled sheets.
- Downspouts – Vertical drainage pipes from gutter to ground. Usually rectangular profiles.
Flashing and Trim
Roll formed flashing and trim products help seal gaps and transitions:
- Eave flashing – Seals panel edges along eaves. Formed with z-profile.
- Ridge caps – Covers roof ridge. Made from angular panels.
- Rake flashing – Seals panel ends at roof edges.
- Valley flashing – Covers open valleys between roof sections.
- Pipe flashings – Seals gaps where pipes penetrate the roof.
Structural Products
Structural roll formed products provide roof bracing and support:
- Purlins – Horizontal beam supporting rafters. C or Z-shaped.
- Girts – Horizontal beam supporting wall panels. C or Z-shaped.
- Eave struts – Supports edge of roof overhang. Angled profile.
- Base angles – Mounting flange for equipment curbs. L-shaped.
By combining different standard and custom roll formed sections, complete installed roof systems can be manufactured.
Benefits of Roll Formed Roofing Products
There are many good reasons roll forming has become the dominant manufacturing process for metal roofing components:
- High productivity – Up to 100 ft/min line speeds possible with minimal labor.
- Low tooling cost – Rolls are far less expensive than stamping dies. Faster product changeovers.
- Material savings – Process scrap minimized. Nearly 100% material utilization.
- Flexibility – Many profiles possible from the same initial flat coil.
- Simplicity – Provides “ready-to-install” finished panels and sheets.
- Strength – Cold forming work hardens the metal, increasing its strength.
- Quality – Consistent, repetitive forming ensures uniformity.
- Versatility – Small batch custom and specialty profiles feasible.
The combination of low cost and flexibility makes roll forming ideal for roofing manufacturers. The same equipment can make multiple products by simply changing the roll tooling.
Typical Specifications of Roofing Roll Forming Machines
Roofing roll formers come in different widths and production rates to suit specific applications. Here are some typical machine specifications:
- Width – 24 to 72 inches wide. Matches panel width.
- Thickness – Can form metal up to 1.5 inch thick. Typical is 0.03 to 0.25 inches.
- Speed – Up to 100 ft/min. Higher for thinner gauge material.
- Stations – Around 8 to 20 forming stations. More allow more complex shapes.
- Drives – 10 to 40 horsepower main drive motors. Servo feeds.
- Controls – PLC/HMI and industrial PC. Touchscreen interface.
- Material – Forms steel, stainless, aluminum, copper.
- Coatings – Handles prepainted, galvanized, and coated coils.
- Tooling – Quick-change roll cassettes. Knurled or machined rolls.
Many standard roofing profiles can be made on a 24 to 36 inch, 10-12 station roll former. Custom profiles may need wider machines or more stations.
Roofing Roll Forming Machine Manufacturers
There are many equipment manufacturers that specialize in roll forming technology. Some leading global suppliers of roofing roll formers include:
- Samco Machinery – Taiwanese company making roofing lines for over 30 years.
- Voestalpine Roll Forming Corp – European roll forming equipment manufacturer.
- ATC Automation – Canadian manufacturer focused on metal building components.
- Mark Specialty Metal Products – Producer of erection equipment and roll forming.
- Apache & Indeco – India-based manufacturer of wide range of roll formers.
- Formtek – UK-based supplier of also section roll formers.
- Metform – Turkish manufacturer of various roll forming lines.
When selecting a supplier, manufacturers should look for ones experienced in roofing products, that offer customized solutions, have a good track record, and provide support services.
How to Choose a Roofing Roll Former
Here are some key considerations when selecting a new or upgraded roll forming machine:
- Products – Determine what profiles are needed now and in the future.
- Width & thickness – Match the machine width and capacity to material requirements.
- Speed – Calculate required hourly or daily production rates.
- Flexible vs. dedicated – Consider if frequent product changeovers are needed.
- Secondary operations – Review what downstream processes may be needed.
- Controls – Ensure the machine control system provides needed functionality.
- Support – Choose a supplier that can provide ongoing service and support.
- Cost – Weigh capital cost against operating costs and capabilities.
Taking the time to thoroughly plan roll former specifications and requirements will help manufacturers pick the right equipment for their production needs and products.
Roll Forming Process Considerations
While roll forming roofing products is very efficient, there are some process considerations that impact quality and productivity. Being aware of these will help optimize the roll forming process.
Roll Design
The contour shape of the rolls directly determines the formed profile. The roll design process is critical to getting the desired end shape accurately and efficiently.
Some roll design factors:
- Developed profile length – Total strip length needed to form the profile. More length = more stations.
- Roll contour complexity – Simpler roll shapes allow faster and easier production.
- Strip thinning – Highly angled bends can thin the metal and lead to splits.
- Unbalanced rolling – Non-symmetrical forms can shift the strip from center.
Roll designs are simulated using CAD software and then machined from steel. Test samples help refine the rolls to get proper material flow and avoid defects.
Metal Properties
The properties of the sheet metal being formed affect the rolling process and final product quality:
- Hardness – Harder material requires higher rolling forces. May require small progression steps.
- Ductility – Allows more extreme bending without splitting or cracking.
- Strength – Stronger metals withstand higher rolling pressures without deforming.
- Surface – Smooth surfaces flow in rolls easier. Coatings can affect lubricity.
Understanding the material properties helps configure the optimal roll pass schedule, processing parameters, and roll design.
Process Factors
Some important process parameters that impact quality and productivity:
- Roll adjustment – Precise roll gaps minimize thin spots or stretching.
- Feed speed – Higher speeds increase throughput but can affect bend radii.
- Roll pressure – Higher pressure improves sharpness but can thin material.
- Roll lubrication – Prevents scratching and increases tool life.
- Tool maintenance – Keep tools sharp and replace worn rolls to prevent defects.
- Vibration – Excessive vibration can blur profiles and cause chatter marks.
Carefully monitoring and controlling these factors improves yield and allows faster roll forming while maintaining quality standards.
Secondary Processing After Roll Forming
After the metal sheet is initially roll formed into the desired profile, some additional processing may be required depending on the product.
Cutoff
The continuously formed strip is cut into set lengths either by a flying shear while still moving or a stop-cutoff shear. The cut panels can then be stacked.
Precise cutoff length is important to ensure properly fitting panels. The shear blades must be regularly maintained to prevent burrs or deformation on the cut edge.
Punching
Some panels require punched slots or holes for fasteners used to attach the roofing to the building structure. These holes can be punched either before roll forming or afterward using a punching press integrated into the line.
Punching before forming allows the use of standard off-the-shelf hole patterns. But it requires very precise roll forming to align the punched holes properly. Punching after forming matches the holes exactly to the panel profile but requires custom punch dies matching the panel shape.
Corrugating
For roof decking panels, transverse bends called corrugations are often formed into the sheets for added stiffness. This can be done by feeding the panels through additional corrugating rolls after initial roll forming.
Curving
For arched roof buildings, panels may need to be longitudinally curved. This can be achieved by running the roll formed sheets through a curving machine to induce the required radius.
Seaming
For certain standing seam panel designs, the vertical seams require clinching together, often by a motorized mechanical seaming apparatus. This folds and interlocks the edges together for weatherproof joining.
Coating
If the sheets require liquid coating, it can be applied by spraying or roll coating in a separate coating line after initial forming. The coating provides corrosion resistance and color.
Embossing
To achieve decorative wood grain or stucco embossed textures, the panels can be re-rolled between embossing rolls after forming and coating. The textured surface provides an attractive aesthetic.
Quality Control
Maintaining high quality standards for roll formed roofing products is essential for proper field performance and customer satisfaction. Some recommended quality control practices include:
Incoming Raw Material Inspection
- Check coil certificate for correct material, thickness, and properties
- Verify surface quality of sheets
- Ensure coils are correctly aligned and undamaged
In-Process Monitoring
- Periodically verify roll formed profile correctness
- Inspect for surface defects like scratches or dents
- Measure cut lengths for accuracy
- Confirm hole locations and alignment
Final Inspection
- Check aesthetic appearance and coating uniformity
- Verify all marks and labels are properly printed
- Ensure packaging provides proper protection
- Validate compliance with quality standards
Process Control
- Regularly audit process parameters – feeds, speeds, pressures
- Perform preventive maintenance and replace worn tooling
- Monitor equipment to ensure alignment and proper settings
- Review statistical process data – dimensions, defects, rejects
Employee Training
- Train operators on proper setup, changeover, and operation
- Encourage focus on quality objectives and accountability
- Provide clear procedures for inspection criteria
- Foster culture of continuous improvement and attention to detail
Safety Best Practices
Working safely is the top priority when operating roofing roll formers. Some key safety practices:
- Enclose or guard all moving parts like rolls and feeds
- Ensure proper machine guarding and safe access for maintenance
- Install emergency stops for immediate shutdown
- Provide obligatory safety disconnects for power isolation
- Follow lockout/tagout procedures for maintenance and cleanup
- Provide adequate workspace clearance around machines
- Eliminate slip and fall hazards around equipment
- Provide hearing protection for noise reduction
- Use machine safety mats that stop motion when triggered
- Clearly label safety decals and provide warning signs
- Keep work areas clean and uncluttered
- Provide overhead drop protection if necessary
- Train all employees on proper operational safety procedures
- Encourage a culture of safety and intervention for unsafe conditions
- Document safety incidents for improvement opportunities
Roll forming equipment can safely manufacture quality product when proper precautions are taken to protect workers.
Conclusion
Roll forming is an efficient, economical process to manufacture metal roofing components in long production runs. It can handle a wide range of materials and thicknesses to produce panels, gutters, and other products with complex cross-sections unattainable by other methods. When the proper equipment is specified and operated effectively with attention to quality control and safety, roofing manufacturers can meet production and profitability goals while satisfying customer needs. roll forming will continue growing as a mainstream manufacturing process thanks to its flexibility, simplicity, precision, and cost advantages along with ongoing advances in technology and capabilities.
FAQ
What is the typical production rate of roofing roll formers?
Production rates vary widely based on the machine width, line speed, and material thickness, but typical roofing lines produce around 600-1000 feet per hour. Higher speeds are possible with thinner gauge material.
What thickness of metal can be roll formed?
Roll formers can typically process sheet metal ranging from 0.01 inch thick foils up to about 0.25 inch thick structural steels. The maximum thickness depends on the machine’s power and rigidity.
What type of drive systems are used?
Roofing roll formers mainly use electric servo motor drives for the feed system. The main roll stations are driven either by gearboxes or direct drive motors mounted along the shafts.
How quickly can roll tooling be changed over?
With quick-change cartridge style roll sets, profile changeover can usually be accomplished in 30-90 minutes. Fixed tooling changes take longer around 4+ hours.
What secondary operations can be integrated?
Typical integrated operations include punching, curving, cutting, seaming, corrugating, embossing, and coating/painting by various methods.
What is the installed cost range for roofing roll formers?
Installed costs typically range from around $150,000 to $500,000 depending on the size, production rate, and features. Larger or custom machines with many stations can cost $1 million or more.
What should be considered for roll former maintenance?
Critical maintenance items are roll and bearing inspection/replacement, lubrication, belt tensioning, monitoring alignments and tolerances, cleaning, and overall preventative maintenance.
What safety devices should be included?
Safety items like e-stops, entry gates, guarding, safety mats, alarms, and services disconnects should be used. Lockout procedures are essential.
How long is the return on investment period?
With the labor and tooling cost savings, ROI timeframes of 12-24 months are typical for most roofing roll forming machine investments.