The Nozzle Plate

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1. Introduction

The nozzle plate (or nipple plate - the terms are interchangeable) is a small, simple, but important part of most type casting machines. It provides an interface between the melting pot's nozzle and the back side of the mold. Simultaneously, it also forms the back surface of the mold's casting cavity.

Machines which use nozzle plates: Nozzle plates are necessary in all pivotal type casting machines, and are important elements of the design of most other kinds of type casters used in type foundry operations (the Thompson, for example, and the Barth, the Küstermann "system Foucher" casters, the Hakko, etc.) 1 .

Machines which integrate this function into the mold: The nozzle plate does not appear as a separate part on the Monotype Composition Caster or its derivative, the Type-&-Rule Caster 2 . Instead, in these machines the nozzle fits directly into a conical hole in the base plate of the mold.

Machines which do not use nozzle plates: Nozzle plates are not used in composing Linecasters such as the Linotype or Intertype or in noncomposing Linecasters such as the Ludlow Typograph or the (confusingly named and rare) All-Purpose-Linotype . In these machines the role of the nozzle is played by a larger, generally flat-fronted (for the Linotype) or flat-topped (for the Ludlow) component called a mouthpiece. This mouthpiece bears directly on the flat back (or bottom) of the mold.

The concept of the nozzle plate doesn't apply at all to the true continuous stripcasting of the Elrod.

Machines I'm not yet sure of: I do not know the Lanston Monotype Giant Caster or the (English) Monotype Super Caster well enough to say whether a separate nozzle plate was used in them. I suspect not. I don't know Monotype fusion strip casting technology well enough to say whether nozzle plates are used with it. 3 . Again, I suspect not.

Contents/Organization:

Since most readers who do not have practical experience running typecasters will not yet know what a nozzle plate is, first I'll illustrate two characteristic forms of the Nozzle Plate (on the Thompson and on Pivotal Caster) and then go in to more specific topics:

[QUESTIONS: Is there a nozzle plate on post-1878 Fouchers? Is there a nozzle plate on the Man-Nen? Is there a nozzle plate on Man-Nen derivatives such as the ZD-201?]

[TO DO: nozzle plates on other casters. Küstermann. Hakko.]

[TO DO: Investigate which Asian casters had heated nozzle plates.]

2. The Nozzle Plate on the Thompson

The Thompson Type Caster has a simple but well-developed form of nozzle plate, and may serve to illustrate its function clearly.

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The nozzle plate goes on the back (pot side) of the mold, with its flat side against the back of the mold. Here's a view of it sitting in place (with the pot swung back out of the way), together with a view of it being removed.

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If you look closely in the top view in the illustration above, you'll observe that the round hole in the nozzle plate doesn't quite line up with the jet ejector of the mold. In other words, just sitting there it is too low on the mold. This is correct for this particular view. In use, the nozzle plate is located by the nozzle on the pot, and is therefore raised up to its correct alignment. The nozzle plate "floats", held in place only by being clamped between the nozzle and the back of the mold.

Here's a view from the mold side. The pot is still swung back out of the way, but I've artificially raised the nozzle plate up to align with the mold cavity.

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Here's a view of the pot and the nozle, with the nozzle plate held (by hand) near the nozzle. You can see how the roughly hemispherical nozzle fits into the hemispherical depression in this side of the nozzle plate.

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Here are two views of the nozzle plate locked in place by the pot. Yes, in operation the wire handle gets very hot.

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3. The Nozzle Plate on Pivotal Type Casters

The nozzle plate on a Thompson is vertical, because that orientation is convenient for its use on the machine. You hold it there by its wire handle and lock it in place by swinging the pot in. Once it's locked up, it does not move at all until for some reason you swing the pot back again.

In a pivotal type caster, the nozzle plate is just as important, but the style of operation is entirely different. In a pivotal, the mold swings up to and then back away from the nozzle on each casting cycle. So the machine itself must hold the nozzle plate in place. This is done most easily by designing a slightly different form of nozzle plate such that it is held loosely by two studs on the pot. (This was of course the original style of nipple plate from 1828, as attested by Bruce's 1845 patent.)

Here's a photograph of the nozzle plate on my pivotal type caster. This particular machine was manufactured in England and spent its working life in India. Its date of manufacture is unknown, but it is visually identical to casters shown in photographs of the Caslon foundry in London in 1900.

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Here it is from the pot side. If you zoom in on this photograph you can see that the depression for the nozzle is little more than a small dimple in the plate.

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And here it is locked up. (The pot is cold. I've loosened the choker and pot levers so I won't break anything and have just cycled the machine, cold, by hand.)

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If you want to see a clear view of a slightly different (and a bit nicer) pivotal caster nozzle plate, take a look at the video posted to flickr by Patrick Goossens, at: https://www.flickr.com/photos/61708911@N04/22407330598/

4. The Mold Base Plate on Monotype Composition and Type-&-Rule Casters

In the Monotype Composition Caster (as made by either the Lanston Monotype Machine Company in the US or by The Monotype Corporation Limited in England), and in its sorts casting derivatives such as the configuration of the machine best known as the "Type-&-Rule Caster" 4 , there is no separate nozzle plate. Instead the functions of the nozzle plate, which are:

are performed by the base plate of the mold. This base plate is an integral part of the mold. If you remove the mold, the base plate comes with it. The mold and its base plate are fixed in place during operation.

Here are two photographs of a mold for a Type-&-Rule Caster showing the top and bottom. In the machine, the nozzle points vertically upward and the mold is mounted horizontally above it. The pot and nozzle can be raised and lowered by the operator. Note the conical hole in the bottom of the mold. This is where the nozzle goes in.

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5. Origin of the Nozzle Plate

The nozzle plate was invented before the machine we generally regard as the first successful type casting machine (that is, David Bruce, Jr.'s pivotal type casters of 1838 and 1843), but until 1845 it was not used on Bruce's pivotal type casters. The nozzle plate was invented in 1828 by William Johnson, 5 for White's New York Type Foundry. Bruce's first two patents do not use a nozzle plate, but instead use unsatisfactory alternatives.

Johnson used the nozzle plate in a machine which he patented on 1828-08-21. This patent, for "Casting Printers' Types," has been lost, but is now retroactively assigned the US "X-patent" number 5,197X. But Bruce cites Johnson's patent explicitly in his own patent of 1845 (his third patent for pivotal type casters, US No. 4,072) , saying that for this machine he has adopted a nozzle plate "of the same construction as that patented by W. Johnson August 21 1828" (p. 2, col. 1)

We know nothing else of the details of Johnson's machine. It is now considered "unsuccessful," but much of our opinion in that regard is due to Bruce's remarks that Johnson's "machines were mere experiments, & finally abandoned" ( {Bruce 1981}, p. 53). This same 1828 Johnson machine also introduced the force pump into casting machinery.

Figure 2 of Bruce's 1845 patent is the oldest surviving illustration of a nozzle plate ("nipple plate" as it is termed in the patent). Here it is from a scan done by me of an old photostat done by someone unknown of an actual printed copy of this patent (not the dreadful digitizations which are now the only versions surviving at the USPTO). The nipple plate is the item marked 't' on studs 's' and 's' at the upper right of the caster as shown. This is clearly identical to nozzle plate on my own pivotal type caster, shown later

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(For complete versions of the plates from Bruce's patent, see the presentation of it in the Notebook on pivotal type caster literature.)

6. Why Have a Nozzle Plate?

The nozzle plate can be a very toublesome part of the machine. Why have it at all?

In all type casting machines which have a pot which can be separated from the mold, and a nozzle on that pot, some apparatus is necessary to interface the nozzle to the mold. A nozzle plate does this as a removable component (which also forms the back surface of the mold cavity). The base plate of the Monotype Composition/Type-&-Rule Caster does the same thing as a fixed part of the mold.

The primary difference between the two approaches is that the nozzle place "floats" and permits some amount of misalignment between the pot/nozzle and the mold. With a nozzle plate the nozzle aperture may be misaligned slightly in the up/down and left-right directions. Because the nozzle and its receiving seat in the nozzle plate are curved, the angle of the nozzle relative to the front-back axis of the mold may also be slightly misaligned.

Intuitively this seems as if it would be an advantage on pivotal casters, which must engage the mold and nozzle once per casting cycle. This must have been especially true in earlier machines, made with 1840s vintage machine shop equipment. We'll never know why Johnson invented the nozzle plate in 1828, as we have no details of the design of his machine. But we know that Bruce experimented with alternative systems before adopting Johnson's nozzle plate in 1845, and found it to be superior to them.

Logically, there are several possible reasons why the nozzle plate might have been used on later machines in which the pot and mold were locked together throughout the casting process: It may be that this feature was simply carried over from pivotal caster technology without thinking. It may be that the "floating" nature of the nozzle plate permitted more economical machine construction. (The cheapest parts are those which don't exist. The original Thompson, for example, had no method of vertical pot adjustment, and even in later machines this was done using inexpensive shims.) It may be that this "floating" nature provided easier operation. (Aligning the nozzle to the mold is a more involved operation in the Monotype Composition Caster than it is on the Thompson, for example.) There may well be other reasons. My current hunch is that all of these reasons are in some degree true. But I'm just guessing. We may never really know.

7. The Nozzle Plate on Barth Type Casters

We are fortunate that the American Type Founders engineering drawing for the nipple plate for Barth type casters in sizes 6-24pt survives. This gives us important metallurgical information for nozzle plates as they were constructed in the early 20th century. For a more complete discussion of this, see the page of ATF Technical Drawings in the Notebook on the Barth Type Caster. Here's a reduced resolution version of it:

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This drawing specifies the steel alloy to be used: "L-XX". This, it turns out, was a trade name for a particular alloy of "high-speed" steel ("L-XX High Speed Brand") formerly manufactured by the Atlas Crucible Company of Dunkirk, NY. It has been suggested by some in the typecasting community that this was a "special" alloy which is no longer available. This is not true. While this particular brand is no longer available, its specifications are simply those of type T1 high-speed steel, which is a standard alloy still available commercially.

This does, however, raise an interesting question. The " high speed steels," so called because they were suitable for what was then high-speed cutting in machine tools, were developed from the very late 1890s. Their significant property is "red hardness"; they retain their hardness at the elevated temperatures of aggressive metal cutting. This naturally makes them suitable for nozzle plates. But what alloys were used from 1828 to 1899? Mushet steel (which was air-hardening and which retained its hardness at elevated temperatures) was only invented in 1868. Even if it was adopted immediately, that still leaves a period from 1828 (or really 1845) to 1868 unexplained.

8. Nozzle Plates on Other Casters

[TO DO]

Küstermann, "system Foucher"

Hakko and/or Hakko derivatives.

[TO DO: understand, and then illustrate this] Davis pivotal caster. Legros & Grant, p. 307, discuss the Davis pivotal type caster, which differed from other pivotals in that the type discharged from it was set up on a stick during delivery (most pivotals simply discharge the type into a chute). They note that the Davis had a "two part" nipple plate, by which they meant one of two thicknesses of metal which on its mold-side formed a conical extension to the jet. This, they say, aided in keeping the type from "turning over" during dischange.

9. Heated Nozzle Plates

[TO DO]

[Some casters in the far east (including either a Hakko or a Hakko copy) had heated nozzle plates. I am unaware of any such refinements appearing on western machines - though many times I wished the Thompson was so equipped!]

10. Notes

1. A nozzle plate was used in early machines by Foucher, but I have not yet been able to discover whether a nozzle plate was used in the influential 1878 Foucher and later machines. It would be surprising if it was not, since both the the Küstermann "system Foucher" machines and the Barth have nozzle plates, and they were derived from the Foucher. But I have been able to find no evidence regarding the Foucher itself.

2. The Type-&-Rule Caster is the name under which the sorts casting variation of the Monotype Composition Caster was known.

3. The "fusion casting" technology used by both Monotype companies for all of their stripcasting is in principle entirely unlike the true continuous stripcasting introduced by the Elrod. The two Monotype companies applied this fusion-casting technology to all of their sorts casting machines (Type-&-Rule Caster, Giant Caster, Super Caster). Lanston Monotype also manufactured a dedicated fusion-casting machine, the Monotype Material Making Machine (and a barely attested derivative, the Material Maker Jr.)

4. Confusingly, so called even when not fitted with fusion stripcasting equipments.

5. William M. Johnson, of Hempstead, Long Island, should not be conflated with Lawrence Johnson (1801-1860), who together with Georg F. Smith purchased the Binny & Ronaldson Type Foundry.

11. Bibliography

{Bruce 1981} Bruce, David, Jr., ed. James Eckman. History of Typefounding in the United States. [1874, 1885] NY: The Typophiles, 1981.