Fine Blanking: The Ultimate Guide

Fine blanking is a popular sheet metal fabrication process. This guide will take you through all vital aspects of fine blanking process – keep reading to learn more.

What Is Fine Blanking?

Fine blanking involves a special type of stamping method which uses two opposite dies. Unlike other conventional blanking methods, fine blanking will produce parts with high accuracy, perfect flatness, enhanced edge characteristics and precision.

Advantages Of Fine Blanking

Clean, Smooth Finishes
Clean, Smooth Finishes

Fine blanking creates smooth and clean surfaces that may not require additional finishes.

Complex Designs Possible
Complex Designs Possible

Through fine blanking, various complex part shapes can be achieved.

Wide Range Of Materials
Wide Range Of Materials

A variety of materials can be used with fine blanking including heavy metals and tool steel.

Perfect Part Flatness
Perfect Part Flatness

With fine blanking parts acquire the kind of flatness that is not possible with the conventional methods.

Fine Blanking Material Options

Aluminum; Aluminum has good thermal and electrical conductivity with good malleability.

Copper; Copper is very economical, lightweight, formable, durable and recyclable material.

Cold Rolled Steel; Cold rolled steel offers durability and high strength and it is easy to form.

Titanium; Titanium is easy to form and it offers resistance to corrosion and durability.

Exotic Alloys; Exotic alloys offer resistance to oxidation and corrosion with high durability.

300 Series Stainless Steel; 300 series stainless steel is durable and formable offering resistance to corrosion with non-magnetic properties.

400 Series Stainless Steel; 400 series stainless steel is strong and offers perfect surface finishes.

Fine Blanking Material Options
Tolerances In Fine Blanking Process

Tolerances In Fine Blanking Process

Precision fine blanking offers the following technical requirements;

  • Dimensional tolerances normally depend on material thickness, part shape, quality of tools, press adjustments and lubricants.
  • Generally, tolerance capability of precision fine blanking is approximately above +/- 0010’’.
  • Flatness tolerance varies with shape, size, thickness and other mechanical properties of the material.

Thicker parts are flatter compared to thinner parts.

  • Perpendicularity tolerance is determined by material thickness, position of cutting edge, press adjustment, die rigidity.

However, the approximated tolerance is almost at 900

  • Surface quality depends on properties, material type, die quality, lubricant, condition of cutting edge.

Fine Blanking Vs Conventional Blanking

Fine blanking involves a stamping force that blanks materials through the use of both top and bottom pressures. The counter pressure from the bottom is used to minimize the need for clearance. On the other hand, conventional blanking lack the counter pressure hence the need for clearance between punch and die.

Parts Produced

Fine blanking can create parts that are finished and functional with no need for other secondary finishes. On the other hand, conventional blanking with the high-speed cutting impact, materials are teared and the end product is crooked.

This needs secondary finishes to get the part ready for various applications. Another difference between the two techniques is that fact that fine blanking can create smaller parts compared to conventional blanking.

Cost

In terms of the tooling cost, conventional blanking is cheaper compared to fine blanking methods. However, fine blanking is more economical when compared to conventional blanking when working with large volumes of products. Therefore, fine blanking is mostly recommended for companies dealing with high throughput productions.

Speed And Efficiency

Conventional blanking processes are slightly faster compared to the fine blanking process because it only creates the cuts. Fine blanking is slower because the process involves other tools that ensures that part is smooth and flat.

Accuracy And Precision

Fine blanking is a good choice compared to conventional blanking when one is interested in superior flatness, tight dimensional tolerances. In terms of accuracy and precision, fine blanking is much better because it produces finished and functional parts.

Fine Blanking Vs Conventional Blanking

How Fine Blanking Process Works

How Fine Blanking Process Works
How Fine Blanking Process Works

Die Opening

Before opening the die, all the required parameters are set and the machine is put ready for the whole process. Now the first step in the fine blanking process involves the opening of the die through the provided opening mechanisms.

Material Feed

Second step is the feeding of the material into the die, manually or automatically. The material is in the form of thin or thick sheet metals. While feeding the material, ensure that the blanking line is placed appropriately to ensure accuracy.

Embedding The Material

After feeding the material, it is important to apply pressure through a ring jig that will ensure that the material is secured. This is to ensure that the material does not move during punching to avoid formation of cracks and fracture on surfaces.

Die Closing

After the material has been fed into the die, it is closed. Closing the die creates a blanking line on the material separating material inside and material outside the cutting edge.

Blanking

A pressure and a counterpressure are applied to the blanking line which separates the punch and the waste. Blanking force and pressing force are applied throughout the whole blanking process. The punch is moved from the start to the end of the material during blanking. A stamp with the required shape is used for cutting the material.

Separating Part From Waste

After blanking, the punched part remains in the die while the waste is deposited onto the dropout die. For effective progressive production, other processing procedures are incorporated in the system including stamping, countersinking and offsetting.

Pressure Withdrawal

After separating the punch and the bore waste, the pressure and the counter pressure forces are withdrawn. Pressing force is applied to aid in blanking the material while the counterpressure is applied to secure the material in place.

Removal Of Parts

The die is then opened and the produced part is exposed and is ready to be ejected from the die. Counter pressure is applied again at this stage to push the parts out through the die opening.

Cleaning Of The Die Area

Air blasts or alternatively mechanical sweeps are used to get rid of part or slug from the working surface of the die.

Getting The Die Ready For The Next Cycle

Once the process is over and the machine has been cleaned, it is set and put ready for the next cycle of fine blanking.

Equipment For Fine Blanking

Equipment For Fine Blanking
Equipment For Fine Blanking

V-ring

V-ring is a ridge which is V-shaped usually placed on either the stinger plate or die plate or both. When used and placed on the stinger plate, it is placed in a distance half of the thickness of the material. V-ring is responsible for pressing into the material to avoid movement of material during the blanking or stamping procedures.

Punches

Both movable and fixed punch die designs are available for progressive and single procedures respectively. Punches are used for blanking materials during the fine blanking processes. The two types of punches available include fixed punch, used for more complex and larger parts and sliding punch, for smaller parts.

Die Cavity

A straight die cavity is recommended for fine blanking processes to ensure accuracy and precision by preventing expansion.

Cutting Edges

Fine blanking requires cutting edges that are radiused to let the material to flow through the die cavity.

Fine Blanking Technical Requirements

Fine Blanking Technical Requirements
Fine Blanking Technical Requirements

Fine Blanking Surface Quality

The quality of a fine blanked part is dependent on the properties, material type, cutting edge, die quality and lubricant. A blanking surface has the structure composed of surface roughness, burr surface, splitting surface and sunk surface.

Perpendicularity Tolerance

Angular tolerances between the blanking surface of a part and the surface cause non-perpendicularity. They are dependent on condition of the cutting edge, material thickness, die rigidity and press adjustment. Basically, if the material is 1mm thick, then non-perpendicularity should be 0.0026mm.

Flatness Tolerance

Flatness of a given part is the deviation of the plane. While in their pressed states, parts display high flatness. However, part flatness is determined by the shape, size and thickness of material.

Note that parts that are thicker are very straight compared to those that are thinner. Also, materials with low strength are flatter than those with high strength. Another factor is that a material with a greater pressing force is flatter than one with a less.

Dimensional Tolerances

Dimensional tolerances vary depending on lubricants used, how the press is adjusted, properties of material and how thick the material is. Basically, tolerances are tighter since the process is more accurate and precise.

Fine Blanking Vs Progressive Die Stamping

Fine Blanking
Fine Blanking

Fine blanking can be referred to as a high precision blanking. The shape of a part from the outside can be achieved through fine blanking using a die. A specialized stamping press is used in this process to apply equal pressure on the material from the top and the bottom.

Equal amount of pressure from the top and the bottom ensures flat edges and smooth surfaces. Parts produced through fine blanking have no fracture zones and they appear smooth and square edges. Fine blanked parts have tight dimensional and flatness tolerances hence eliminating secondary finishes like milling or grinding.

Progressive Die Stamping
Progressive Die Stamping

Progressive die stamping is a metal stamping method that employs the use of progressive dies set up within one die. The process is fast and produces in high volumes performing at a single pass of the press like in forming or piercing.

Like in fine blanking, progressive die stamping also produces products that do not need secondary finishes. Material feeding is done on a strip via the various press stations hence cutting the edge into sections. Progressive die stamping can handle several parts at the same time leading to production as high as 1500 parts every minute.

Limitations Of Fine Blanking

High Tooling Cost
High Tooling Cost

In order to set up a fine blanking system, a lot of money is required, limiting smaller companies that are just starting up their operations. Companies would prefer to go for cheaper techniques to save up on the tooling cost.

Low Speed
Low Speed

Fine blanking has various advantages over the conventional blanking methods and other blanking methods including precision, accuracy, tighter tolerances and flatness. However, when it comes to production speed, it is slower and throughput is low.

Cannot Produce Multilevel Products
Cannot Produce Multilevel Products

Generally, fine blanking can produce parts with complex geometries and can work with large parts with high complexity or smaller parts. However, unlike MIM or other similar methods, fine blanking cannot produce parts with multi levels making it limited.

A Lot of Waste Created
A Lot of Waste Created

During the fine blanking processes, a lot of waste is produced and some of them are not recyclable. MIM is deemed better because it does not produce waste products which is important especially when dealing with expensive raw materials.

Training Needed
Training Needed

For accuracy and better parts, the operator has to undergo training to be able to operate the fine blanking equipment.

Applications Of Fine Blanking

Automotive Industry
Automotive Industry

Fine blanking is useful in the automotive industry for making precise components such as powertrain or seat adjustment for cars. Fine blanking also produces parts that ensure that applications like safety belts, brake system or airbag are in good condition.

Electronical Industry
Electronical Industry

Parts that are used for switching applications in electricity, data and energy supply are made through fine blanking. Some of the materials used for such applications include copper, aluminum and steel. These materials are all compatible with fine blanking processes and can be used comfortably.

Medical Industry
Medical Industry

In the medical industry, accuracy and precision are factors that are of utmost importance and fine blanking offers all these benefits. Products such as implants, scissors, blades and spatulas must be sterile and precise to avoid mistakes during medical procedures.

Manufacturing Industries
Manufacturing Industries

Various parts produced through fine blanking have their applications in the manufacturing industries for making tools, devices and various equipment. Other manufacturing industries use fine blanking for making parts that are accurate and precise with tight tolerances for various applications.

Aerospace Industry
Aerospace Industry

Just like in the automotive industry, various components within the aerospace industry consider precision and accuracy as important.

Lawn And Garden
Lawn And Garden

Parts such as soil knife, spade shovel, soil rake leaf rake and lawn mower parts are made through fine blanking techniques.

People Also Ask:

How Does Fine Blanking Compare To Stamping?

Fine blanking has various advantages over stamping including production of smaller parts, tight dimensional tolerances, great flatness etc. However, considering cost of production, stamping would be much cheaper if no secondary operations are needed.

Another factor that makes the two techniques different is the fact that stamping controls material tearing during the process. On the other hand, fine blanking prevents material tearing during the process of making parts.

What Are The Different Types Of Blanking Techniques?
  • Compound die stamping
  • Continuous strip blanking
  • Progressive die stamping
  • Square sheared blanking
  • Cut off blanking
  • Fine blanking
Is Precision Fine Blanking Accurate?

Precision fine blanking is a highly accurate technique useful for producing parts that require tight tolerances compared to other methods. Precision fine blanking is recommended for applications such as the medical industry where accuracy, precision and sterility are important factors.

Resources:

Fine Blanking Process

Blanking And Piercing

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