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  • Posted on 20th July 2017 in the categories: CNC Machining

    CNC Machining Throughout History

    CNC Machining in action

    The vast variety of products available to engineers today is astounding, but it wasn’t always this way. There was a time when metal components had to be heated, hammered, shaped, and manipulated to produce one simple component. There was a time when early machines had to be meticulously put-together, piece by piece. However, today’s modern CNC systems have changed the way components are manufactured, making it a more efficient and accurate process.

    From NC to CNC machining

    CNC machining has changed vastly throughout history, proving nearly as complex as today’s CNC systems. The original version of CNC technology first came about after WW2. This version was developed as a dependable means to manufacture high quality parts for the aerospace industry.

    Development of the machines

    The predecessor of CNC was numerical control (NC). NC was initially established by John Parsons, who developed it to produce hardened aircraft coatings. Prior to this, Parsons had been part of the team who developed a system that produced helicopter propeller templates. During this development, Parsons discovered that by using an IBM 602A multiplier, it was possible to calculate air foil coordinates. The data gathered was then inputted into to a Swiss jig borer which produced templates on punched cards.

    This discovery lead to many Air Force research projects at MIT starting in 1949. After widespread research and development, an experimental milling machine was created.

    Forming the foundation of this experimental system was a 28-inch Cincinnati Hydro-Tel vertical-spindle contour milling machine. Some adjustments were made to improve the system, including:

    • Exclusion of tables
    • Exclusion of head drives and controls
    • The installation of three variable-speed hydraulic transmissions, which were connected to leadscrews

    It was proven that each transmission could produce a 0.0005” signal of the head, cross-slide, or table for each electrical pulse it received from the director. This was done through gearing and leadscrews. Wanting to ensure that the machine was functioning as directed, a feedback system was included. Synchronous motors were geared to each motion, this in turn produced voltage in response to movement. This voltage then sent feedback to the detector for comparison against the original command voltage.

    The data obtained by 1953, through various application studies highlighted the possibility of newer, promising technology. Though, another experimental NC machine had also been developed at MIT. One that was different and less accurate. This NC machine used a flexowriter, vacuum-tube electronic control systems, a tape reader and eight-column paper tape. Evidently, this machine provided the basis to what became known as CNC machining today.

    Punch tape to software programs

    Originally, NC punch tape cards were created with a flexowriter. Punch cards were inserted into a control unit which was adjacent to the machinery, and stamped with a programming sequence called G-Code.

    NC machines established the industry standard, until the mid-1960s.  The 1960’s introduced the first CNC machines. CNC technology followed the same principles set by the original NC system, but replaced the punch tape method with a more technological advanced computer software program. This new programming technology quickly replaced NC machining as the industrial standard. CNC also paved the way for subsequent processes, such as computer-aided design (CAD) and computer-aided manufacturing (CAM). Although, similar to the machining punch card system created in 1952, CAD/CAM provides today’s manufacturers with greater flexibility in their operations.

    Controller evolution

    In the 1950s and 60s, NC machines employed vacuum tubes and mechanical relays as their primary controller sets. At that time, the controllers were “point A to point B” locators that functioned along two axes. However, today’s high-density integrated circuits provide the capability of creating 3D shapes in a vast range of designs and dimensions. Today’s modern controllers can also communicate with the user, then store and analyse the program data.

    Sophisticated CNC Machinery can automatically monitor the quality of the work being performed. For instance, if the controller notices a defect in the intended product design, it can sometimes make a correction in real-time by replacing dull tools or notifying the manufacturer about any problems. This level of automation highlights the key difference between the two conceptually similar programming methods. While NC controllers must function within the parameters of direct, simple tasks, CNC programming enables machinery to analyse data and adapt to changing circumstances.

    Advantages of CNC machining

    Since CNC machining has evolved over the decades, its current form is more advanced in terms of precision, automation, and production speed than any of its earlier forms. Some benefits provided by today’s CNC machining include:

    • CNC machining may reduce the number of machines required for a project.
    • CNC programs can be easily modified, making them adaptable to a wide range of machining tasks.
    • Shorter CNC machine set-up and integration times result in greater production productivity.
    • There is less need for lengthy machining trial runs under CNC programs.
    • Quality control and equipment inspection systems can be semi- or fully automated.CNC Machine

    Goudsmit UK

    For more information visit our web-page or download our products and services brochure.

    Contact us today for more information at info@goudsmit.co.uk or if you’d like to speak to a member of our team call us on +44 (0) 2890 271 001.

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