راهنمای کامل برش، خمکاری و جوشکاری ورق‌های فلزی

مقدمه

Sheet metal fabrication is essential for a wide range of manufacturing processes, from the creation of simple toys to complex aircraft components. Despite its widespread use, understanding how this process works is crucial. This article provides a detailed overview of the techniques and materials involved in sheet metal fabrication.

1.0What Is Sheet Metal Fabrication?

Sheet metal fabrication is the process of forming flat metal sheets into desired parts and products through operations such as cutting, folding, bending, and assembling.

Common materials used include steel, aluminum, stainless steel, brass, copper, and zinc. Sheet metal thickness typically ranges from 0.006 to 0.25 inches. Thicker gauges are suitable for heavy-duty applications, while thinner sheets are better for applications requiring malleability.

2.0Sheet Metal Cutting Techniques

Cutting processes are used to separate metal sheets into parts and shapes. Cutting techniques can be broadly divided into:阿

2.1Laser Cutting

Laser cutting is a thermal process that melts metals locally using focused laser beams. The beam is absorbed into the material, vaporizing it, while a cutting nozzle injects gas (usually nitrogen or oxygen) to remove molten material and protect the cutting head.

Laser cutting is suitable for materials such as stainless steel, mild steel, and some non-ferrous metals. Reflective materials like aluminum may require fiber lasers. Typical thickness capacity ranges from 20 mm to 40 mm.

2.2Plasma Cutting

This thermal process uses ionized gas (plasma) to melt and cut through metal. The method is only effective on electrically conductive materials and is often used for thicker sheets (up to 50 mm), where surface finish is not critical.

Suitable materials: Aluminum, stainless steel, copper, brass

مزایا:

• High-speed cutting
• Automation capability
• Suitable for high-strength metals with low heat input

Disadvantages:

• High power consumption
• Potential noise during dry cutting

2.3Waterjet Cutting

Waterjet cutting uses a high-pressure stream of water—often around 60,000 psi—to cut through metals. Pure waterjets are used for soft materials, while abrasive waterjets cut hard metals like carbon steel and aluminum.

مزایا:

• No heat-affected zones
• Excellent surface finish without burrs
• Can cut a wide variety of materials

Disadvantages:

• High-pressure systems may cause bending
• Requires support fixtures to prevent distortion

2.4خالی کردن

Blanking uses a punch and die to remove a piece from sheet metal. The punched-out part becomes the final component, while the leftover sheet is scrap.

مزایا:

• High dimensional accuracy
• Custom part production with good repeatability

Disadvantages:

• Slower than punching
• Higher tooling cost

2.5Shearing

Shearing is used to cut straight lines on flat sheet metal using high-pressure blades. It’s ideal for high-volume cutting of soft metals that don’t require a clean finish.

مزایا:

• Fast, economical for large batches
• Simple, effective for straight cuts

Disadvantages:

• Produces burrs and deformations
• Not suitable for applications needing clean edges

2.6Sawing

Sawing uses sawtooth blades to gradually remove material. Horizontal band saws are used for bar stock sizing, while vertical saws perform complex contour cutting.

مزایا:

• High cutting accuracy
• Low material waste due to small kerf
• Supports a variety of non-ferrous materials

Disadvantages:

• Less contact stability during flat sheet cutting
• Inconsistencies in surface finish

2.7Punching

Punching uses shear force to create holes in sheet metal. Unlike blanking, the removed piece is scrap, and the sheet remains as the final component.

مزایا:

• High-speed hole making
• Clean and precise cuts
• No thermal distortion

Disadvantages:

Setup requires precise tool and die alignment

9 روش پانچ ورق فلزی که هر سازنده‌ای باید بداند

3.0Sheet Metal Forming Techniques

Forming involves reshaping metal while it remains in solid state. This section outlines the main forming processes used in fabrication.

3.1خم شدن

Common Bending Techniques:

مزایا:

• Good mechanical properties in final parts
• Cost-effective for low to medium volume production

Disadvantages:

Springback can affect accuracy

3.2Hemming

Hemming folds sheet metal over onto itself, typically in two stages:

• Bending into a V-die
• Flattening in a die to produce the hem

مزایا:

• Reinforces edges
• Improves aesthetics
• High dimensional control

Disadvantages:

Risk of material deformation

3.3Rolling

Sheet metal rolling reduces thickness using spinning rollers. It can be classified as:

• Hot rolling: Above recrystallization temperature
• Cold rolling: At or near room temperature

Common applications: Pipes, tubes, stampings, discs, wheels

مزایا:

• High-speed, high-efficiency
• Consistent thickness
• Tight tolerances achievable

Disadvantages:

• Requires high initial investment
• More suitable for mass production

Plate Rolling Processes Explained: Three-Roll, Four-Roll, and Cone Shaping Techniques

3.4مهر زنی

Stamping uses dies and presses to cold-form sheet metal. The process may involve bending, punching, embossing, and flanging in a single operation.

Materials: Stainless steel, aluminum, brass, copper

مزایا:

• Low labor and tool cost
• Easy automation
• High repeatability

Disadvantages:

• Expensive to modify dies once production starts

Complete Guide to Sheet Metal Stamping Dies and Processes

3.5Curling

Curling creates circular, hollow edges for safety and edge strength. Typically performed in three stages:

• Initial curve forming
• Rolling the curve
• Curl closure

مزایا:

• Eliminates sharp edges
• Strengthens component edges

Disadvantages:

• Can introduce burrs or deformations

3.6Metal Spinning

Spinning reshapes metal discs over a mandrel using rotation and a forming roller.

Materials: Stainless steel, aluminum, brass, copper

مزایا:

• Suitable for hollow, symmetrical shapes
• Flexible for small and large batches

Disadvantages:

• Limited to concentric designs
• Size and shape constraints

What Is Metal Spinning ? Process Types, Machines, and Applications

4.0Sheet Metal Joining Techniques

Joining is critical to assembling fabricated components. The main methods include welding and riveting.

4.1Welding

Notes:

• Stick welding is fast but can overheat thin metals
• MIG is ideal for automation but unsuitable outdoors
• TIG offers clean welds but requires skilled labor

4.2Riveting

Riveting is a semi-permanent, non-thermal joining method. It involves drilling holes and forming rivet tails to secure sheets.

Types:

مزایا:

• Cost-effective and easy to inspect
• Suitable for lightweight metals

Disadvantages:

• Adds weight
• Weakens structure due to drilled holes
• Creates noise in mechanical assemblies

5.0نتیجه‌گیری

Sheet metal fabrication combines cutting, forming, joining, and finishing processes to produce a vast range of industrial and commercial components. Choosing the right technique depends on part geometry, material type, cost, and production volume. With advancements in machinery and automation, sheet metal fabrication continues to evolve, offering greater precision, speed, and flexibility.

6.0Frequently Asked Questions (FAQ) about Sheet Metal Fabrication

Q1: What is the difference between laser cutting and plasma cutting?
A: Laser cutting uses focused light to vaporize material, offering high precision and clean edges, while plasma cutting uses ionized gas to melt conductive metals. Laser cutting is better for thin, intricate parts; plasma is preferred for thicker, high-strength metals.

Q2: Which materials are most commonly used in sheet metal fabrication?
A: The most common materials include stainless steel, aluminum, mild steel, copper, and brass. Choice depends on strength, corrosion resistance, formability, and application.

Q3: What is the typical thickness range for sheet metal?
A: Sheet metal thickness usually ranges from 0.006 inches (0.15 mm) to 0.25 inches (6.35 mm). Thicker materials are considered plate, while thinner sheets are called foil.

Q4: How accurate is CNC bending in sheet metal forming?
A: CNC bending provides high repeatability and tight tolerances, often within ±0.1 mm, depending on material and equipment.

Q5: Is welding or riveting better for sheet metal assembly?
A: Welding offers stronger, permanent joints ideal for structural integrity. Riveting is better for lightweight, modular designs or when heat distortion must be avoided.