December 2012 Archives

(1) Automation of press process

When roughly categorizing the automation of press process, it can be expressed as follows.

1) Automating the material to be pressed
2) Automating single-shot press operations (Formation of progressive working)
3) Automating inter-press operation material transfers

1) and 3) since the item (2) requires expertise of press die designer. By automating the 1) and 3), press accuracy (quality), deformation prevention, productivity and safety improvements can be obtained.

(2) Automation of press operation and quality

By automating the items 1) and 3), following quality improvements are obtained.

(1) Reduction in irregular variations of press accuracies by stabilized material feed lengths.
(2) Reduction in deformations on pressed products during transfers between press operations.

The nature of pressed products renders automating difficult due to complex shapes, and burrs. Therefore, it is especially important that the pressed products are to be designed for ease of automation (asymmetrical shape designs, etc.)

(3) Examples of notable points regarding press operation automation

-With automation of material feeding operations, configuration and placement designs of Material Guides are of the importance. The material guides have functions to properly retain and feed the coiled material into dies.

-In general, the height and width of the material guide are properly to be +0.02~+0.03 mm in relation to the coiled material dimensions.

-It is unavoidable that the materials have transfer variation factors such as twists, bows, slit width variations, etc.

-Clearances of guide sections due to material guide parts wear and friction resistance variations due to presence or absence of oil will relate to instability in material feeding.

(From: Nagumo Seisakusyo Corp. catalog)

Products that require electronic controls, including consumer electrical appliances, all include some sort of electronic printed circuit boards ([Photo]).

-During the period when the Japanese assembly industries advanced towards overseas, there was a time where many of the PC board production lines have adopted manual assembly workers in production lines, though assembly automation has already been realized in Japan.

-Since the labor costs were low in those locations where the Japanese businesses have advanced at that time, the production lines were designed and constructed based on a concept of "errors would be eliminated at inspection process stages".

-However, the manual inspections could not completely eliminate inspection misses due to human labor nature, even as the inspections were re-inspected, and zero defects was never accomplished.

-On the other hand, automated mounter can (1) inspect mounted parts, (2) confirm mounting positions, (3) check the soldering conditions, and (4) inspect functionalities of the PC boards, and incidence of failure can be kept to ppm order.

-This, however, is stipulated on a precondition that the automated mounter is properly maintained (especially the preventative maintenance).

-Based on the two production methods mentioned above, also with the limitations of manual labor, low cost automation has gradually progressed into the oversea advancements.

-It is difficult for automated machines to process while determining the instabilities in shapes and performances of the parts handled. Conversely, the advantage of skilled workers is able to overcome such shortcomings of automated machines.

-Therefore, the abilities of skilled workers are useful for prototypes during the early stages of new product development, where as for the mass production phase is the turn for the automated machines.

-For high density mounted components, human operations are difficult even for the early stage prototypes. Low cost automation not prioritizing the process speeds will be needed.

Explanations on molded platic product extraction automation and quality improvements

-Flowability of molten plastics largely depend on the melting temperature. This melting temperature of the molten plastic is significantly effected by the contact surface temperature of the mold after being injected into the mold.

-The mold has coolant recirculating to maintain within a certain initial temperature range.

-This cooling effect acts as a variation factor of mold temperature drop if molded prodct extraction cycle time and following idle time vary.

-[Fig.1] is an example of manual extraction of molded product, and it shows that the work cycle time is variable.

-Therefore, stablizing each of the work cycle time of the jnjection molding process leads to stablization of the mold temperature, and leads to molding quality stabilization by stablizing the flowability of the molten plastic ([Fig.2][Fig.3]).

-For the automation of molded product extraction/low cost automation, a 2 axis robot and a gripper mechanism are used.

-When automating extraction using low cost automation, MISUMI single axis robot RSH and standard components app. Example: Belt Driven Shuttle Unit ([Fig.5]) can be the application reference.

(From: Yushin Precision Equipment Co., Ltd.)

The plastic injection molding process ([Fig.1]).

- Molded plastic products are produced by heat melting thermoplastic resin with a resin heat melting section ([Fig.2]) of a injection molding machine ([Fig.2]), and high pressure injecting the fluidized plastic into a mold ([Fig.3]), filling the cavities formed inside the mold and cooled to solidify into molded plastic products ([Fig.4]).

- The fixed side mold on the left above ([Fig.3]) is placed with the top side shown in the photo facing down on the movable side mold shown on the right below to form a cavity for melted resin.

- After one cycle of this molding process is completed, the mold top and bottom are separated and the molded plastic part is extracted. There are methods of extraction by manual process and unmanned process using robots.

(From Nissei Jyushi Kogyo Corp. HP)