GB2287954A - Alloy - Google Patents

Abstract

A coin or token alloy having a composition by weight percentage of 68.5 to 71.5 copper, 1.7 to 2.3 nickel and the balance being zinc. Preferred impurity maxima are 0.05% Fe, 0.05% Mn and 0.01% Pb.

Description

Alloy The present invention relates to an alloy and more particularly but not exclusively to an alloy for use with gaming tokens and coins.

A large number of gambling machines use gaming tokens or coins rather than actual currency in order to reduce security problems associated with holding large volumes of cash. Previously, these tokens have been made of freely available alloys such as ASTM 752 which has a composition of 65% Cu, 17% Ni and 18% Zn.

Obviously, a persistant problem is the use of slugs or counterfect gaming tokens. These slugs are made of any available material provided they have roughly the same dimensions and weight of a legitimate token. Such slugs allow the gaming machines to be played and thus will allow payment in legitimate gaming tokens which can then be cashed.

In order to reduce the problem with slugs, a typical gambling machine will include a coin detector or acceptor mechanism. Usually these acceptor mechanisms check the token diameter, weight and an electrical property such as conductivity. Such checking eliminates the casual use of illegitimate slugs or similar sized coins. However, there are some determined individuals who manufacture slugs that can fool these acceptor mechanisms.

It will be appreciated that it is relatively simple to manufacture slugs of roughly the right size and weight. However, analysis of the coin is required to determine an appropriate material or alloy to provide the necessary electrical property to consistantly fool an acceptor mechanism.

It is an objective of the present invention to provide an alloy for making gaming tokens that is hard to replicate as a slug.

In accordance with the present invention there is provided an alloy for manufacture of gaming tokens, the alloy having a composition in the range 68.5% - 71.5% Cu, 1.7% - 2.3% Ni and the balance made up of Zinc but with limits as to impurities are follows 0.05% Fe, 0.05% Mn and 0.01% Pb to give a conductivity level of 18-20% on the International Annealed Copper Standard (IACS) when annealed and cleaned.

Preferably, the alloys composition is 70% Cu, 2% Ni and 28% Zn.

Preferably, the alloy is made into discs suitable for striking as coins or tokens.

An embodiment of the present invention will now be described by way of example only.

As discussed above the principal alloy used for manufacture of gaming tokens in the past was ASTM 752.

This alloy is freely available in the commercial market and so is available to forgers.

Most coin acceptors use surface electrical conductivity alongside sizing and weight as their acceptance criteria. For the alloys under consideration the International Annealed Copper Standard (IACS) is used. Thus, copper is considered to have a 100% conductivity under this IACS regime. The alloy ASTM 752 has a conductivity of 3-5% IACS when clean and freshly annealed. It will be understood by one skilled in the art that there are a wide range of alloys that have this level of conductivity so slugs can be made from a wide range of scrap metals etc.

The present alloy has a nominal composition of 70% Cu, 2% Ni, 28% Zn. This gives a conductivity of 18-20% IACS when clean and annealed. It will be appreciated that such conductivity levels are uncommon in widely available alloys. So it is more difficult to make operative slugs.

It will be appreciated that close control of alloy conductivity is at the core of the present invention.

However, the present alloy may still be operative in the following composition ranges 68.5% - 71.5% Cu, 1.7 - 2.3% Ni, balance Zn with limits as to impurities of 0.05% Fe, 0.05% Mn and 0.01% Pb.

With such unusual conductivity it is possible to get the acceptor acceptance ranges to tighter specification. Thus, even though a counterfeit token may have the right weight and dimensions it will not pass the conductivity test.

Typically, acceptor circuitry comprises a pair of induction coils either side of a roll chute or slide.

The tokens or coins slide or roll passed the coils where their electrical conductivity is determined. It will thus be appreciated that within reasonable limits any size and thickness of token or coin can be manufactured.

The present alloy is made by casting, rolling and annealing using normal foundry practice.

Claims (7)

What we claim is:

1. An alloy comprising by weight percentage 68.5 71.5 copper, 1.7 - 2.3 nickel, the balance being zinc and incidental impurites.

2. An alloy as claimed in claim 1 in which the following incidental impurities have respective maximum values by weight percentage: 0.05 iron, 0.05 manganese and 0.01 lead.

3. An alloy as claimed in claim 1 or claim 2 which contains by weight percentage 70 copper.

4. An alloy as claimed in any preceding claim which contains by weight percentage 2 nickel.

5. An alloy as claimed in any preceding claim which contains by weight percentage 28 zinc.

6. A method of manufacturing coins or tokens comprising preparing an alloy as claimed in any preceding claim, making it into discs and striking such discs into coins or tokens.

7. A coin or token having an electrical conductivity of 18 - 20% on the International Annealed Copper Standard (IACS).