Plate Rolls: The Manufacturer’s Buying Guide to Finding the Best Option to Improve Roll Operations

What is plate rolling and how do you select the right type and size plate roll with so many options available? Plate rolling is an incredibly essential process of metal fabrication. Since most of the products created during plate rolling are sophisticated, cutting-edge and unique, they are created using specialized equipment that is known as the plate rolling machine or the plate bending machine. In this article, we’ll take a look at what a plate roll machine is and its use in the manufacturing industry. 

What Is Plate Rolling?

Plate Rolling is a unique process whereby a sheet of steel, aluminum, stainless or other material is formed into circular or other shapes by force through a set of powered rollers. Machines consisting of 2 to 4 roll sets press, engage and form the material through force of electrically, mechanically or hydraulically driven means. It involves the rolling of flat sheet metal to create cylindrical items such as pipes, tanker trailers, buckets, and pressure vessels.

What Is a Plate Roll Machine? 

A plate roll machine is a piece of equipment that is used to roll various types of sheet metal into round, semi round, round with varying radii or conical shapes (some machines specialize in rolling materials back to flat too!). The rolling machine boasts a working mechanism that allows it to bend flat sheet metal into a large arc or cylinder or even a square, an ellipse shape and a multi-section arc. Utilizing a series of precise and strong hardened rolls powered by either hydraulic or mechanical methods, the rolls are brought into a pitching position with the material desired to be shaped. Once the material is firmly held between two of the rolls, a third and sometimes fourth roll is brought into position pushing the material causing the initial bend, or what is referred to as the pre-bend. The rolls then begin to rotate pulling material through the pinched rolls and past the pushing rolls forcing an arc into the material. 

What Are Plate Rollers Used For?

This process forms many common parts we see everyday such as;

• Propane Tanks
• “Tin” Cans
• Fuel Tanker Trucks
• Water Tanks
• Piping
• Heavy Equipment Accessories 

Types of Plate Rollers

Since not all rolled metals are created equal, every project may require a specialized type of plate roll machine. Therefore, you should expect to find a vast array of plate rollers in the market. The type of equipment you choose should be based on the complexity and uniqueness of the customer's orders. Some of the standard metal rolling machines include: 

• 2 Roll Machines (Ideal for thin, highly repetitive circular rolling such as Food Cans)
• 3 Roll Initial Pinch (Most popular design due mostly to cost)
• 3 Roll Double Pinch (Affordable design for heavier bending applications)
• 3 Roll Variable Translating Geometry (Affordable Design for Variable Radii applications)
• 4 Roll Double Pinch (The most versatile of the designs) 
• Vertical Rolls (Perfect when rolling very large Radii such as above ground fuel and water storage tanks)
• Automated Cycle & Specialty Rolls (Spiral Duct Rolls, Corrugated Material Rolls etc.)

The two roll plate machines are designed to bend flat sheet metals with a width of up to 8-12” and 12 Gage thickness. This makes them ideal for batch production of thin cylindrical items used in household appliances such as filter canisters, food canisters and of course, tin cans.  

Three roll sheet rolling machines can be further classified into asymmetrical, horizontal lower roller move type and geometric variable plate rollers. Although all tools in this category operate using different principles, they are all used to bend medium to thick plates. The three-roll sheet bending machines are commonly used not only in general fabricating but also in chemical, boiler, shipbuilding, metal structure, petroleum and machinery manufacturing industries. 

The 4-roll plate bending machines are renowned for transforming flat sheet metal into spherical body, cone tube body or other shapes. Four roll plate bending machines are more productive, precise, safer, versatile, and easier to operate than the rest. Once the material is set and pinched the two rolls on either side of the pinched roll do all the work without having to remove the plate and rotate it for pre bending both ends. They can roll up to 8”  thick plate steel and are most likely to be outfitted with CNC controllers for variable radii applications and  complex shapes such as elliptic and polycentric workpieces. Their greatest advantage is that they can be used on a wide range of sheet metals and can also accept a high degree of automation. They can also be used to roll tube segments, ovals, rounded boxes and other shapes.  

How to Identify the Right Plate Rolling Machine 

Choosing the right type of plate roll is the first step. As there are various types available and at various prices When it comes to choosing a plate roll, alongside choosing the correct type it’s imperative that you get the correct size. If the size of the plate roll doesn’t match your application you’re going to waste your money unnecessarily. Getting the right type and size for the job should be a priority. To determine what size of plate roll you’re going to need or benefit from the most you’ll need to consider the types of applications, the material you will be rolling mostly and the operator skill level you have to work with.

Choose the type of plate roll that will perform your work the fastest with the least amount of intervention involved. As 2-Roll machines are dedicated to one specific type of application they are not well suited for the job shop. In most job shops and plate production facilities we see a large variety of initial pinch, pyramid style 3-Roll and 4-Roll machines. For simple round sections an initial pinch or 3 Roll Double Pinch Design can be selected, however for more complex geometry a Variable Translating Geometry or 4-Roll machine with CNC Controls should be used. Of these selections the choice can be made easily as follows: 

• • 3 Roll Initial Pinch
    • Pros: Cheapest Design, simple to operate with small sheets with limited thicknesses
    • Cons: Material must be rotated to pre-bend each end manually causing labor intensive operation
  • 3 Roll Double Pinch
    • Pros: Cheapest Design for Heavier plate Bending Applications 
    • Cons: Material Slippage during forming possible. Difficult Angle of Material approach
  • 3 Roll Variable Translating Geometry
    • Pros: Cheapest Design for rolling with variable Radii (Rounds-to-flat-to-round)
    • Cons: Material Slippage is likely without skilled operation
  • 4 Roll Double Pinch (The most versatile of the designs) 
    • Pros: Easiest to operate from small to larger sizes. Material does not need to be removed for pre bending operation. Easily can be automated with CNC controls
    • Cons: Price

How to Select the Plate Roll Size for Your Application

Once you have selected the correct type of plate roll for your application, it’s imperative that you get the correct size. If the size of the plate roll doesn’t match your application and material you’re going to waste your money unnecessarily. Getting the right type AND size for the job should be a priority. To determine what size of plate roll you’re going to need or benefit from the most you’ll need to consider the material types, thicknesses and yield strength you are intending to use it for. 

Also noted, you should consider that a machine designed to form 1” (25MM) Grade 50 steel plate will not perform well attempting to roll 16GA material as the rolls are simply too large. Conversely, a machine designed to run ¼” (6MM) X 4’ (1250MM) material cannot roll the 1” (25MM) material or any material at all wider than 4’. The critical factors you need to consider in selecting the right sized plate roll are: 

• • Bending Length: The overall rolling capacity is determined by the physical length of the rolls. When purchasing a plate roll make sure you are sizing the roll length for the maximum width of material you will be rolling, understanding that the longer the rolls the larger the roll diameter has to be in order to maintain strength under rolling pressure. The adverse reflection of that is the larger the diameter you will need to be rolling. 
  • Minimum Diameter: The minimum diameter is the smallest diameter you desire to roll your material into. Use the factors 1.5X the top roll diameter for easy, no problem, rolling in one pass to achieve this goal.  1.3X the top roll diameter can be achieved with multiple passes or material at a shorter length than the full width capacity of the pallet roll. 1.1X the diameter of the top roll is also achievable in softer materials less then the full width of the rolls AND utilizing a multipass technique. 
  • Bending Capacity: Bending Capacity on a plate roll is the capacity at full width the machine is capable of. Rated in mild steel, a ¼” X 10’ plate roll is capable of bending ¼” thick mild steel in a 10’ width to 1.5X the top roll diameter in a single pass but be careful as it may not be able to pre-bend that same material. 
  • Pre-Bending Capacity: Pre-Bend is the initial bend a plate roll operator must make before actually rolling the material. The process involves pinching the material firmly between two of the rolls and then using the side or lateral roll to force the material into an initial bend before rolling commences.This process must be repeated on each end of the plate being rolled to avoid large flattened sections at the mating ends of the cylinder. Pre-Bend capacity is always less than that of the rated bending capacity so it is important to ensure the rolling system you are looking at can properly pre-bend the material you are working with.
  • Yield Strength: The yield strength is the strength of the material you are rolling, or better put, the strength of resistance to bending that the material has. The harder the material the higher the yield strength and the larger/stronger the plate roll must be to roll the material. Yield points vary greatly from Aluminum to Stainless and other materials in between. Make sure you know the Yield strength of your material as plate rolls are all offered on a mild steel (30,000 PSI) yield strength rating but can be sized in accordance with your needs.

Find the Best New & Used Plate Rollers At BendmakUSA

At BendmakUSA our staff and network of partner distributors are experts at helping you select the right plate roll for your needs and budget. We understand the challenges of fabricators and work hard to ensure you make the right choice in not only a machine type and size, but in your machine tool supplier partner as well.  Connect with us to learn more about Plate Rolls and the equipment available from BendmakUSA.