アルミニウム平版の砂目立てについて

残留研摩砂の除去に関する実験

抄録

According to LTF's study, the residual abrasive on grained surface of aluminum plate -the adhesion of abrasive to the surface as anchoring or imbedded mud- is said to be the cause of toubles in platemaking and printing. This paper is an abstract of report of the experiment the writers made on the removal of abrasive.
For the experiment, we prepared an aluminum-magnesium alloy non-corrosive plate (1MT-H, 52S-1/2H) and a zinc plate of 1dm², On the assumption that the diffrence in weight of the plate before and after the graining represents the quantity of residual abrasive, following 4 tests have been made;-
a. Effects of abrasives and graining balls according to their classification.
b. Effects of grain sizes of abrasives.
c. Effects cf graining times.
d. Effects of additions of anionic surface action agent (Teepol) to lubricants.
From those tests, following results have been derived;-
a) Generally speaking, the quantity of residual abrasive on aluminum plates is larger than on zine plates.
Among silica-sand, garnet and aluminum oxids, garnet proves the largest in residual quantity. We used for tests steel balls of 10mm, 15mm and 19mm and steatite ball of 20mm in diameter in graining and it proves the quantity of residual abrasive is the smallest when steatite balls are used and in the case of steel balls, the larger diameter of balls, ie, the the heavier of the weight of balls, the larger is the quantity of abrasive residue. (Fig. 2)
b) Regarding grain size, on aluminum plates, #180 leaves the largest quantity of abrasive residue and if the grains are coarser or finer than the said critical size, the residual quantity of abrasive becomes smaller. (Fig. 4)
Regarding graining time, the residual quantity of abrasive increases in line with increase of graining time but after 30 minutes, no noticeable increase takes place. (Fig. 6)
c) The addition of teepol to lubricant proves to give a very good effect and it reduces the residual quantity of abrasive by half. As it has been proven of above mentioned test results that the residual quantity of abrasive is in increase proportion with the weight of marbles, we made further tests with 6mm steel balls. Compared with tests with 10mm steel balls and 20mm steatite balls, the decline in residual quantity of abrasive is not conspicuous but 6mm steel balls give very finer grains and are considered best suited for aluminum plate working. (Fig. 13)
From the results of desensitization test with aluminum plates grained with 10mm steel balls, we have proven that garnet is unsuitable and silica-sand is best suited for abrasion aluminum plates.
Regarding etch solution, one consisting of ammonium bichromate, phosphoric acid and gum arabic is best suited and Post-Brunak also takes quite a good effect. (Fig. 15)