overwhelming features (particularly for a beginner), it is easier to understand individual parts by a simple separation into two distinct sections:
▪Control Panel
▪Operation Panel
To make such distinction or such separation, it is important to know some background of CNC machine manufacturing.
CNC machine tools are manufactured by companies that have expertise in building machine tools. Without suggesting any preferences and their origin, well known companies that manufacture CNC machining centers and have a large presence in North America are OKK®, Mori-Seiki®, Matsuura®, Makino®, Haas®, Fadal®, Mitsubishi®, Kitamura®, Okuma®, and others. European and Asian markets will be different in the brand names, but these sample names represent machine tool manufacturers regardless of the actual machine origin.
Except for some rare exceptions (Haas, Fadal, Fagor, etc.), most machine tool builders do not manufacture their own control system (the computer part of the machine) - they concentrate at what they do best, which is building machine tools. On the other hand, each CNC machine tool requires a CNC control system.
Just as there are CNC machine tool manufacturers that do not make their own controls, there are CNC control system manufacturers that do not make their own machine tools (except some minor exceptions). The reasoning is quite simple - ‘we know what we’re good at and specialize in doing it’.
Those machine tool manufacturers that make no control systems of their own do only one thing - they purchase the control system that supports their machines.
That also means there is a field of manufacturing that specializes in design and manufacturing of the computer portion of the CNC machine only - the actual control manufacturer. Names such as Fanuc®, Yasnac®, Mitsubishi®, Siemens®, Heidenhain®, and many others are all part of this large field.
Let’s sort all this out.
As stated earlier, any control system of a CNC machine can be identified by its two main components:
▪Control Panel
▪Operation Panel
For both operators and programmers, these two control system features form the main area of interest.
Control panel represents the computer part of the CNC machine operations. It is mainly used to make changes in the software part of the system whether in the part program itself or in various software settings, such as offsets and parameters.
Operation Panel represents the hardware part of the CNC machine operations. It is mainly used to change various settings and modes, overrides, and allows manual motions of the machine axes.
The distinction of software/hardware as separate entities is rather simplistic, as both are always connected. At the same time the distinction helps to illustrate the many functions offered by any CNC system.
Every CNC system provides a physical area where a number of part programs can be stored for a period of time. This area is called the system memory.
A program that exceeds the memory capacity cannot be loaded to or run from CNC memory. Even a large memory capacity is always limited, but can be increased by hardware updates. For a CNC operator, it is important to know how much memory is remaining before loading a program. Ideally, all memory capacity should be measured in characters of text, both used and remaining.
The latest controls system DO show memory capacity in characters
Unfortunately, many older controls do not have this facility and use one of two other methods:
▪Memory available as number of pages
▪Memory available as meters or feet
In the first case, the number of pages refers to the number of full screen displays of the program. This is a rather hard way to establish the capacity remaining, and requires some practice. The method of measuring memory capacity in meters or feet seems a bit strange at first, until you understand what meters and feet refer to.
Yes, they refer to the equivalent length of paper tape that used to be the original source of program data in the early stages of numerical control. Although NC or CNC machines using a paper tape today are rather rare, the method of memory capacity measurement has prevailed.
Most current CNC programmers and CNC operators are not familiar with paper tape as the data source and probably have never even seen one. The one reason that the paper tape is even mentioned in a modern handbook such as this is not nostalgia. The reason for its inclusion is the fact that there are still remnants of tape references used on even the most modern CNC systems.
Paper tape was a one inch wide tape, made of special paper (or other material) to exact specifications. Across the tape was a set of odd or even number of holes, punched in different configurations, where each set of holes represented a single character, according to EIA or ISO standard. The separation of one set of punched holes from the next was exactly 0.1000 inches (2.54 mm). This dimension - this 0.1000 inches - is the key to understand memory capacity of a control system, identified in feet or meters.
Keep in mind that this standard has been used around the world, although the base unit was an inch - after all, numerical control technology originated in the United States, where imperial measurements have been predominant (although that is now changing as well). Also keep in mind that most current controls are of either Japanese or German origin, two countries where metric system has been standard for centuries.
The following two tables provide conversions of several common memory capacities, as installed in the control system - the first one converts meters to feet:
The second table converts feet to meters:
As you may expect, it is impossible to list all possible options, but a simple calculation or two will provide the answers required.
First, some conversions of various units, in case they are necessary for additional calculations:
| 1 inch | = | 25.4 mm |
| = | 0.0254 m | |
| 1 foot | = | (25.4 × 12 inches) / 1000 |
| = | 0.3048 m | |
| 1 mm | = | 1 inch / 25.4 |