The key to reducing the cost and lead time of sheet metal parts lies in the difference between the "mold" and "jig" used when making parts. In addition, the "process preparation man-hour" when using molds and jigs will also affect the cost and price. I will introduce design points that cannot be ignored if you want to control the price of sheet metal parts and shorten the lead time from the two parts of molds and jigs.
Image Differences in cost and lead time based on mold type
By slightly changing the shape, the type of "mold" used to make the part is different, and the "man-hours" can be reduced. If you can use "standard molds" and design "less man-hours", you can also suppress the price and delivery time of parts.
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Picture Case (1) Increase the bending height
Only by increasing the height by 1mm, it can be made with standard molds, reducing man-hours, lowering prices, and shortening delivery time.
(In this case, by adopting a design with a height of 8.3mm or more, the mold and man-hours are changed, but the height will vary depending on the part design.)
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Picture Case (2) Increase the bending angle
With only an increase of 30°, standard molds can be used, which reduces man-hours, lowers prices, and shortens lead times.
(In this case, by adopting a design with an angle of 110° or more, the mold and man-hours vary, but the angle varies depending on the part design.)
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Image Differences in cost and lead time based on the need for auxiliary fixtures
One of the points that can reduce the cost and shorten the lead time of sheet metal parts is the difference between the "jigs" used when making parts and their "preparation man-hours".
The process preparation before bending at a designated position is to use a "jig" to fix the material (workpiece). There are two types of "fixtures", permanent and auxiliary, and if it is designed according to the concept of using only "permanent fixtures", it can also reduce preparation man-hours, keep down the price of parts, and shorten the lead time. The public account "Mechanical Engineering Literature", a gas station for engineers!
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Image Unheard of? ! Introduction of jigs used in bending processing!
[Fig. 1] A horizontal view of a workpiece bent with a die
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In bending processing using a processing machine, it is important to firmly fix the workpiece with a jig
Fig. 1 is a view of a workpiece (orange part) bent with a die as viewed from the lateral direction.
In order to bend the workpiece at the black dotted line, orient the workpiece toward the "permanent fixture" called the back stop located on the inner side of the workpiece, abut and fix it in the direction of the arrow, and press the mold on the black dotted line (bending line ) for bending.
If the workpiece deviates during processing, the bending part will also deviate, so it must be firmly fixed. If the workpiece cannot be firmly fixed and the bending process is performed in an unstable state, the bending line will be inclined, resulting in a decrease in accuracy such as dimensional defects.
[Fig. 2] A view of the bending process of other workpieces viewed from above
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"Auxiliary Fixtures" are required when the workpiece cannot be fixed using only "Permanent Fixtures"
Fig. 2 is a diagram of bending processing of other workpieces viewed from above.
As shown in Fig. 2, when the end surface (red line) of the workpiece has a shape that is difficult to abut against the backstop or the abutting surface is small, it is difficult to fix the workpiece using only the "permanent clamp". In such a case, the "auxiliary jig (blue part)" is also used, and process preparation such as marking the bending position is required.
"Necessary process preparation = increase in man-hours" has become an important factor leading to high costs and long lead times.
[Figure 3] Create parallel end faces
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Creates end faces parallel to the bend line, thereby eliminating the need for "auxiliary clamps" and allowing the workpiece to be held in place using only "permanent clamps"
As shown in Figure 3, by creating the end surface (red line) of the workpiece that abuts against the backstop along a straight line parallel to the bending line (black dotted line), the workpiece can be moved using only the "permanent fixture" without the "auxiliary fixture". It is firmly fixed, so the bending process itself can be easily completed without special skills.
Recommended Conditions for Shape
It is recommended that the length (A) of the end face be more than half of the length (B) of the bend (A≥B÷2).
This is because the surface (A) abutting against the backstop is large, and it is easy to fix the workpiece.
[Figure 4] Create parallel end faces with protrusions
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In the case where the end face shown in Fig. 3 cannot be created, as shown in Fig. 4, by creating a protrusion parallel to the bending line (black dotted line), the workpiece can be fixed with only the "permanent jig" without the "auxiliary jig" be firm.
< Recommended conditions for shape >
It is recommended that the length and width (C) of the protrusion shape be 10 mm or more, and the distance (D) from the outer shape to the protrusion be 100 mm or less.
※When the distance (D) from the outer shape to the protrusion is large or the bending length (E) is long, the workpiece will come into contact with the mounting part of the rear stopper, so the workpiece cannot be fixed firmly, and bending may not be possible processing.
Example (3) Create an end face parallel to the bend line (black dotted line)
By creating the end face (the part that abuts the backstop) parallel to the bend line, there is no need for a "secondary clamp". Workpieces can be fixed using only "permanent jigs", reducing process preparation man-hours and reducing prices and delivery times.
Picture Example (4) Create a protrusion parallel to the bend line (black dotted line)
If it is not possible to create an end face parallel to the bend line (the part that abuts the backstop), create a parallel protrusion instead, thereby eliminating the need for a "secondary clamp". Workpieces can be fixed using only "permanent jigs", reducing process preparation man-hours and reducing prices and delivery times.
