The multi spindle screw machine conquers the valve industry
Linea Spindle: an idea, a design, an intuition, a real revolution. A design that came to life after forty years in which Gianfranco Sala, founder of Sala Srl, focused on turning machines working with vertical spindles arranged in line. These machines have conquered the valve market around the world thanks to their precision, production capacity and ergonomics.
In fact, these features were the starting point to resolve the problems of many companies.
“Our machines have always been highly appreciated because they guarantee a level of precision and production capacity necessary in the gas and water valves sector. Many have asked us to use these concepts to also resolve other problems. Linea Spindle was developed to meet these market needs, respecting the dictates of LEAN MANUFACTURING, which we will get to shortly.
Linea Spindle, the first linear multi spindle manufactured in series: what is it?
Thanks to the experience gained in over forty years, we have managed to give life to an innovative machine, characterised by a turning system based on 4 independent vertical spindles with two autonomous loading and unloading units, with the possibility of machining two identical pieces or two different pieces simultaneously. Initially, the idea was to resolve some problems found in traditional turning systems. Therefore, essentially, the rotating bar problem. Along the way, we realised that the Linea Spindle could solve many other problems.
Production Capacity - Precision - No space problems - Flexible production: these are the main features of the Linea Spindle.
Production capacity - Three, twin-spindles would be necessary to obtain the same results as the Linea Spindle. The clear difference depends on the reduced downtime throughout the loading and unloading process: four seconds for the Linea Spindle compared to 12 for the twin-spindles. In fact, times are reduced by one third. The production capacity is the result of a series of factors; one of these is the arrangement in line of the tools, firmly fastened to the structure, without using the rotating tool holder towers. One of the benefits of this setting is chip-to-chip is minimised, i.e. the passage times from one tool to another: an aspect which makes a considerable difference compared to the systems with tool holder towers, used by twin-spindles, where downtime is much longer. On average, the twin-spindle loses approximately 2.5 seconds to pass from tool to tool while, for the LINEA SPINDLE, passage takes just 0.3 seconds. The secret lies in the fact the spindle moves from one tool to another, moving along an axis equipped with a Linear Motor that allows speed to be obtained and, especially, very high accelerations.
Precision - One of the most important requirements of the market is to always have the most precise pieces. An ideal turning system would guarantee the highest precision levels, that remain over time and as long as possible, reducing thermal drift and mechanical wear. During the years of research that led to the development of the Linea Spindle, we realised that this innovative production system definitely represents a solution to turning machine precision problems; the main factors that have allowed results to be achieved, even beyond our expectations, can be summarised as:
- Extremely stable and rigid structure.
- Movements on axes with linear motors and extremely precise optical lines that not only guarantee high precision, but also eliminate use of mechanical components which are therefore not subject to wear.
- Thermal stabilisation both of the electro-spindles and the axes with linear motors, to avoid thermal drift and therefore improve precision.
No space problems - Space is an important issue in companies. Bar loaders are large tools that move bars even up to 6 metres long. The need, for each machine, to be supported by a bar loader is therefore something that has significant consequences in terms of space and even safety. The Linea Spindle eliminates all these problems, as well as the safety risks for workers.
Flexible production - Flexibility is word like any other, often used by companies to define their machines. But when are machines truly flexible? The answer lies in the set-up time, or rather, the time necessary to carry out a full series of actions to allow passage from the last good piece of a batch to the first good piece of the next batch. For rapid set-up, an entire series of operations are necessary:
- cleaning the machine
- replacement of tools and referencing the new work program.
- performing the new work cycle.
- quality control and validation of the new piece to start production.
1) Cleaning: it is important to clean the work area as quickly as possible; the ergonomics of the LINEA SPINDLE with the vertical spindles, arranged in a frontal position - makes cleaning the machine very simple and fast.
2) Tools replacement: also in this case, the ergonomics of the LINEA SPINDLE proves extremely valid. Not having to work on the tool holder tower rotations, the tools are within the operator’s reach: their immediate accessibility allows rapid replacement of the tools which thanks to use of the tool holder with CAPTO system were already preset with extreme precision outside the machine.
3) and 4) Work cycle and quality control:
Moreover, the issue of tool change, is one of the more delicate aspects, given the importance it plays in the production process. In particular, when the tools in question are highly important. In a traditional multi spindle, for example, each tool interacts with all the other spindles, whether six or eight. This means that in the set-up time, the change of a single tool must be considered, making it necessary to check and validate all the pieces manufactured by all the tools needed, before production restart. Instead, with Linea Spindle, each tool interacts with a single spindle, making it much quicker to replace and validate a single piece and ensure quicker restart of the machine in production.
However, the truly unique features of the LINEA SPINDLE is it drastically reduces set-up time, retooling the machine without having to completely stop the production cycle. How is this possible?
The trick lies in the setting and architecture of the machine itself, which results as being divided in two completely independent work areas.
This allows, for example, replacement of a single tool, but also the possibility of tooling a new production on one side of the machine, keeping the other two spindles in production.
As you can imagine, in this case the set-up time (“downtime” when the machine is not manufacturing”) is automatically halved.
Versatility - LINEA SPINDLE is the only standard multi spindle machine that indifferently produces both from bars and retouching, i.e. from raw pieces obtained with various technologies, such as cold forging, hot forging, casting, sintering, etc."