Common Defects Found in High Volume Runs & How to Prevent Them

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Avoiding defects is a major goal in metal stamping. Over time, machinery needs recalibration, and punches and tools need sharpening or realignment. If these issues are ignored, stampings may drift out of tolerance, leading to extra time and money for rework.

Your stamping partner should value quality control as much as you do. At Keats Manufacturing, we are always watching for defects and out-of-tolerance stampings during manufacturing and with specialized inspection methods. Keep reading to learn more.

Defect Rates

In small production runs, it’s often possible to inspect individual stampings manually – this is not so much the case at high volumes. Defect rates can soar if problems are not fixed early. Stampers turn to inspection methods that use computers and automation to find defects and errors while maintaining efficiency.

One option is coordinate measuring machines or CMMs. These devices use delicate probes or vision cameras to physically or optically assess a part’s dimensions and features. By comparing the part against stored coordinate data or a digital image, CMMs identify when a part is out of tolerance.

To speed up the process, specialized fixturing is used to position multiple parts for inspection at once. This helps operators maintain their workflow while incorporating quality control.

Forming and Dimensional Defects

Forming and dimensional defects can occur as a result of the material used, worn or improperly assembled tooling, or design problems like defect-prone part features or specifications that are challenging to achieve.

Defects or problems that appear repeatedly signal a stamping error. Identifying and resolving them quickly makes it easier to avoid scrap and rework and minimizes the risk of defective parts reaching you or your customers.

Forming Defects

Metal forming is the process of changing the shape of a metal workpiece without adding or removing material. Common examples of forming defects include:

  • Cracking and tearing
  • Galling or scratching
  • Misalignment or shifting inside the press
  • Incorrect punch or guide angles

Dimensional Defects

Metal stamping involves changing the shape of a workpiece by cutting, punching, shearing, blanking, or otherwise removing material to create a finished part. Defective parts are often out of tolerance, which affects their fit and function in an assembly or finished product.

Common sheet metal stamping defects include:

  • Twisting, wrinkles, or improper flatness
  • Incorrect hole placement, size, or shape
  • Incorrect bend angles or springback
  • Burrs and deformed edges
  • Overall part length/width defects

Stamping defects are often caused by a misaligned material feed, worn or broken punches, material defects, improper force or tonnage, or other problems.

Packaging Defects

Packaging mistakes can also lead to damaged parts, scrap and rework, fulfillment delays, and extra expenses.

Incorrect or Missing Shipping Markings and Barcodes

Incorrect barcodes or labels in the wrong place are inconvenient in smaller orders, and it only compounds in a high-volume production run. It takes time and money to relabel dozens or hundreds of boxes and cases, or to recheck part numbers, shipping info, or dimensional details. That in turn causes fulfillment delays, so it’s critical that inspection includes checks for these errors.

Container and Product Defects

Components may be packaged manually by workers or with automated or semi-automated equipment, or even a combination. Regardless of the method, parts can be damaged if they are packed incorrectly, jostled and scratched, or if the packaging itself is damaged, bent, or torn. Some packaging methods like tape and reel encapsulation for very small parts, or custom trays to isolate individual parts, can prevent damage during packaging.

Another important step is the final inspection of packed parts. This ensures packaging is correct and no defective parts were missed in earlier inspections. It can be done by workers as they pack items or with machine vision equipment, comparing an image of a correctly packed tray or box with items as they exit the packaging line.

Metal Stamping Services From Keats Manufacturing

Errors and defects can happen at many points in the stamping and packaging process. That’s why you should work with a manufacturer who prioritizes attention to detail at every turn and has taken the steps to mitigate the risk of defects.

At Keats Manufacturing ee are ISO:9001, ISO:14001, and IATF:16949 certified. We provide high-quality metal stamping and finishing services with careful inspection and packaging to meet your needs. Contact us to learn more or request a quote to start your order.

What Is Metal Stamping?

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Metal stamping is a versatile and efficient method for fabricating parts and components. Stamping achieves tight tolerances with many types of metal in different thicknesses. It offers high repeatability and can be performed manually or with semi- or fully-automated equipment.

Here we will look at the steps in the metal stamping process, common materials used, and the industries and applications that rely on it.

Metal Stamping Explained

Stamping is used to create specific part shapes and geometries from flat metal material. The process can include a wide variety of forming techniques, including blanking, bending, punching, embossing, progressive die stamping, and more.

The steps in the metal stamping process include:

  • Design and Tooling Preparation. Designers create a plan of stamping operations to manufacture parts efficiently while minimizing scrap. Factors include the part’s intended end use, material properties and behaviors, dimensions and tolerances required, and sometimes, aesthetics. Computer-aided manufacturing (CAM) or computer-aided design (CAD) software is used to create a three-dimensional graphic model of the part and to develop the corresponding tooling. Tooling is then manufactured from hardened tool steel.
  • Material Selection. Metal for stamping comes in sheets or coils in varying thicknesses. Material selection is based on mechanical and chemical properties, press tonnage, material availability, and material cost. These are considered in relation to design intent, production volume, and timeframe for manufacturing.
  • Feeding. Sheets or coiled strips are fed into or through the stamping press. Care must be taken to properly align the material so that the stamping operation and resulting part are within specifications.
  • Stamping. The press strikes the material with heavy force, measured in tons, to create part features. The press opens and the material is removed, and the process is repeated with new material. Any of several operations may be used in the press, including bending, punching, piercing, embossing, drawing, coining, or blanking.

Metal Stamping Materials

Many materials can be used for metal stamping. Depending on the project and its requirements, properties such as strength, ductility, conductivity, corrosion resistance, hardness, bendability, solderability, and surface finish are considerations.

Common metal stamping materials include:

  • Aluminum. Aluminum is a soft metal with a high strength-to-weight ratio. It is ductile and offers good conductivity and corrosion resistance. Aluminum is often alloyed with other metals including zinc, copper, and magnesium to increase its strength.
  • Brass. This alloy is composed of copper and zinc. It is strong, workable, corrosion-resistant, and has an attractive gold-like color that makes it a popular choice for applications where aesthetics are a concern.
  • Carbon Steel. An alloy composed of iron with varying amounts of carbon by weight, carbon steel is classified into low, medium, or high carbon levels. This material offers high strength, great solderability, and cost-effectiveness.
  • Copper. Copper is a soft and malleable metal with a pinkish-orange hue. It is highly ductile, durable, conductive, and resistant to corrosion.
  • Stainless Steel. The addition of chromium makes stainless steel highly resistant to corrosion. It is available in many grades, depending on the amount of chromium content by weight.
  • Other Alloys and Superalloys. Alloys are materials made from mixtures of metal elements in different ratios by weight. Superalloys are mixed metal alloys that can withstand very high temperatures and physical stress. The composition of alloys and superalloys is determined by the desired properties, such as hardness, conductivity, and corrosion resistance.

Metal Stamping Applications

Metal stamping is used across a range of industries for applications requiring high production volumes and tight tolerances. Some common industry uses include:

  • Automotive: Body panels, brackets, battery contacts, and cover plates
  • Electrical and electronics: Clips, tabs, and pins for mobile phones and devices; switches, brackets, terminals, and contacts for appliances and equipment
  • Aerospace: High-strength, lightweight components such as panels, cabin equipment, and other parts throughout aircraft
  • Telecommunications: Switches, router components, contact plates and tabs, power protection components, cabinets, and enclosures
  • Oil and Gas: Connectors, fasteners, brackets, clips, tabs, valves, and metal parts in equipment for oil and gas drilling and exploration applications
  • Medical: Parts for implantable pumps and valves, surgical instrumentation, or hardware and panels used in large equipment and furnishings
  • Construction: Connectors and fasteners for trusses and framing, braces, brackets, cover plates, and enclosures used in systems throughout buildings
  • Industrial Machinery: Components in engines and heavy equipment, tiny parts for electrical systems in machinery, and panels for equipment cabinets

Metal Stamping Services From Keats Manufacturing

Keats Manufacturing has been a leader in the precision metal stamping industry since 1958. We are ISO:9001, ISO:14001, and IATF:16949 certified, with three full-service facilities in North America.

With expertise in four-slide, multi-slide, and progressive metal stamping, we can manufacture custom stampings to meet your application needs. Please contact us to speak with a member of our team, or request a quote today.