The gains come from 3 separate areas
- By controlling the speed of the push and keeping the exit temperature constant we push much faster at the start of the billet and then slow towards the end. This variability during the cycle is always faster than a constant speed push. Typically 10% faster than any manually set constant speed press.
- This is an active control system - it measures the exit temperature 3 times every second. If the billet is too cold, then it will speed-up the push to compensate - if the billet is too hot it will slow the push and avoid a puller breakage or metal deformation. That saves time over the length of a shift by avoiding press down-time. This will typically give a 5% improvement over a shift.
- The human element - different operators - new operators - night shift operators and the general inconsistency of any human based on external inputs. A good analogy is the comparison between an auto transmission and a manual transmission on a car. It doesn’t matter who is driving or the mood / ability of the driver. The auto-box makes the same clean and consistent gear changes day after day. A mistake avoided that would have lead to the press being down for 4 hours contributes a lot to the percentages. Typically gains are 5% over the week.
The Optalex is an active control system - It will compensate for incorrect temperatures of the input billet and give accurate and correct temperatures at he output. In the normal case, the log furnace is a relatively inaccurate device and will easily have a +/-25 Degree variation in output. The Optalex system will compensate for this and hold the extrusion exit temperature to +/-3 Degrees. In addition, should there be a delay in the production cycle, then the billet at the loading stage will be cooling - when the delay is cleared then the cold billet is loaded. The Optalex will cause the press to push harder and hence hold the output temperature at the correct level. The next billet could well have been overheated so the Optalex will cause the press to slow and avoid the possibility of scrap or press down-time.
Because the Optalex extrudes at a constant temperature from the start of the push through to the very end, the metallurgical properties are kept constant throughout. This gives both a consistent surface finish and the dimensional stability that is so important for many customers. If, for instance, the extrusion is to be anodized then a variation in output temperature during the push results in variation in finished color - more scrap and customer dissatisfaction.
One of the big problems facing every extruder is that different shifts and different operators achieve slightly different results from the same die. (these differences may be dimensional / surface quality / metallurgical properties and are caused by the differing parameter settings chosen by each operator.) eX-box offers the extruder a full control system based on operator logging and setting permissions such that a combination of existing control practices and agreed new control parameters allows each die to be run within extremely close limits each time it is used. To provide a feel -
a) When a new die is initially programmed, all the settings / parameters (furnace - press - camera position - exit temperature - puller) must be stored when someone qualified to do the job has deemed it complete.
b) We need access to information on, for instance alloy type or alloy vendor because that changes the characteristics. This info and many other key differentiators are only available on the ‘Factory IT system (not the PLC) so a sophisticated two-way link has to be established with the IT system.
c) When the die is re-run then we can reload all the parameters and the resultant extrusion will be exactly the same as before without the operator having to make a single setting. This can be the case but there are additional things to consider:
i. Has the die been for correction? If so, can the correction have changed the parameter settings. If "Yes" then the die needs to be re-programmed and NOT run automatically.
ii. Are all the press pumps working - if not the pressure characteristics will change and the stored program will be incorrect.
d) There are always minor variations we cannot compensate for so the operator needs to have some leeway - perhaps +/-5C on the temperature - this and many other operator limit settings need to be pre-agreed by the staff & operators before installation. For those not wishing to implement the full ‘consistency’ system, eX-box allows ‘portions’ to be set dependant on management wishes.
From the minute the Optalex is installed, it records all available parameters against every billet ever extruded. The data is stored in an open format Sequel database which is accessible to anyone on the network with the correct permissions. A standard report generator is available with the system and reports are easily modifiable to suit individual requirements. Also, because the system is ‘open architecture’ the user can utilize any ‘third-party’ report generator. The result, better management and control of the overall extrusion and production process, enabling the user to produce the required quality certificates and adhere to the principals & practices of common quality control systems such as ISO 9000.
Based on a conservative 10% gain in metal from the press and a 2% decrease in scrap, the Optalex system will give a ROI of around 3 months. Payback based on cost reduction when not running at full capacity is typically less than 6 months. It is clear that the savings will surpass purchase costs - even with a 1 year lease.
i) Automatic Die Optimization - now available with eX-box. When a new die is introduced the system automatically discovers the optimum conditions and parameters. Provided the operator is satisfied with these conditions he or she presses the ‘save’ button and any future use of that die will cause the same parameters to be used automatically. ii) After a Die change it is normal for a user run a good number of billets to stabilize the temperatures throughout the press. With Optalex, the control of temperature is so accurate, that it is possible to produce good metal on the 1st full billet (see iii below) iii) A user will typically decide on billet length based on the maximum extrusion temperature. Thus he will start the push at the minimum extrusion temperature and aim t end the push at the maximum temperature. That final temperature typically dictates the billet length. With Optalex, the billet can be made longer - it is still more efficient to push slowly at the end of the cycle than stop and enter into the ‘dead’ cycle too early.
Optalex "eX-box" is a network based system. It is only a matter of the permission settings that can constrain any user on the network from gaining access to he system. Of course, the opposite is also true, in that the Optalex can send messages to anyone on the network. Every operation that can be performed using the MWS (Main Work Station) beside the press can also be performed at any remote point on the network. The following are some instances of where the above features are practically applied:-
- Extrusion manager can get a customizable real-time graphical display of press operation and performance on his PC. - Extrusion manager can do the same from his home (via modem, DSL etc) when called with a problem. - Plant manager can have a concise display (small window) showing current ‘pounds per hour’ and shift average ‘pounds per hour’. - Alarm message can be sent to Extrusion Managers PC when press ‘dead cycle’ is greater than 5 minutes. SMS message can also be sent to his cell phone provided network has internet access. - Alarm message can be sent to the Plant Manager when press is inactive for 15 minutes. - Predefined and customizable reports are sent to the email addresses of various staff at varying times of the day. - Optalex service staff can gain access upon request to review performance and analyze potential fault conditions.
Optalex has sold and installed more than 100 systems of its unique ’Total Control System. The record so far is that all those who bought one system and had other suitable presses, also bought further systems.
