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The majority of 6XXX alloy extrusion produced today uses 6063 alloy (or 6060 or a variant of either alloy), and to remain competitive in a tough market the objective is to extrude at maximum speed and productivity.

To this end it is important to use the right billet temperature.  Too high and the maximum possible speed cannot be achieved without surface finish issues or tearing.  Too low and die breakthrough is sluggish, acceleration to target speed is slow and not only does productivity suffer but in addition, too low a billet temperature may well result in too low an exit temperature and the risk of low hardness after age.

Therefore it is critical the correct billet temperature is used to maximize productivity, as illustrated in the limit diagram shown below.  The billet temperature for maximum speed relates to the apex where the two limit lines intersect.

Essentially any single die should be run with a billet temperature that enables breakthrough at maximum available pressure without any acceleration delay.  For most 6063 alloy extrusions the die should be run at a speed to produce an extrusion exit temperature (i.e. on exiting the platen) in the range 1000-1090^oF (495-540^oC), although maximum exit temperatures of 1050^oF (565^oC) are preferred for anodized products.

From the limit diagram, it is not only clear how important selection of the correct billet temperature is, but the importance of billet temperature control is also evident.  Narrow variation in temperature from one billet to the next allows a press operator to select a higher speed without risk of billet temperature variation leading to stalling or surface finish problems.

Furthermore, correct temperature selection and control of the die and container allow optimum and consistent performance.  Dies preheated accurately throughout the thickness to a temperature of 860^oF (460^oC) avoid the need to use hotter starter billets for almost all dies, although some complex hollow dies with delicate tongue features may require special start up practices.  The use of the proven single cell die oven technology is therefore recommended.

Container technology with the ability to set a temperature offset between the top and bottom zones at the front of the container, helps compensate for heat losses into the dies slide and press bed and maintains more even temperature distribution in the die, thus improving die performance in terms of run out variation, shape and consistency of exit temperature.

Extrusion exit temperature increases toward the rear end of the extruded length, and to better optimize the process and achieve the highest extrusion speed throughout any extrusion cycle, constant exit temperature or isothermal extrusion must be achieved by either variable speed control or taper billet preheat where the rear end of the billet is colder than the front.  The approach of variable speed control carries the inherent risk of introducing shape variation, therefore taper billet preheat is preferred.  However traditional gas fired heaters are limited in achieving high enough taper without additional equipment located at billet transfer from the heater to the press.  Such equipment can be an induction heater programmed to tune the already preheated billet to the required taper, or a gas fired nose heater that increases the billet front end temperature, or a quench that reduces the temperature of the billet rear face.  Recent technology incorporates an atomization quench with a liquid boron nitride spray unit.

Therefore, productivity benefits result from correct selection of billet temperature, minimal billet temperature variation, taper billet preheat, and improved management of tooling temperature by correct die preheat and improved container temperature control.

Bill Dixon, QED

The plunger, moving smoothly with a minimum of lubrication, pushes a measured amount of molten alloy through a round and straight shot sleeve, and injects it into the die cavity where it almost instantly hardens.  In that moment, when the liquid alloy is converted into a solid casting, most of the added value, which is the die caster’s livelihood, is generated.  This is the crux of the die casting process, and may be fairly termed, “The moment of casting”.

At one time, in the quest for increased productivity, the component of the die casting process that had the greatest potential for improvement was the die itself.  Not all die casters realize that in recent years this priority has changed considerably.  With the use of three-dimensional computer modeling to predict the ideal flow of metal into the die, and ultra-accurate multi-axis CNC machining to produce a die that can consistently make large convoluted castings with inordinately close tolerances, the die caster should now be able to assume that the dies he is using are likely as good as they need to be.  The best opportunity for improvement therefore now usually lies with the delivery of the alloy into the die.  Analyzing the various forces that impact on the moment of casting, the die caster of today will soon realize that to even approach maximum productivity, the plunger and the shot sleeve must work closely together, since their functions are inseparably combined.

Here’s what should be expected of past and recent graduates:

1) They should continuously challenge the assumptions surrounding them, and use that as formative fuel for their creativity. They need to abandon any attitudes which might cause them to believe that everything is going to stay the same.

2) They should spark imaginative thinking in others.

3) They should focus on opportunity, realizing that continuous disruptive change without action will have negative consequences.

4) They must be prepared to challenge basic assumptions and eliminate habit.

5) They should paint an attractive picture of the future of where the organization is going, and what it will take to get there.

6) They realize that to do their job in the future will require more complex skills.

7) They should approach each day as a new and exciting opportunity. They should spread enthusiasm and excitement.

8) They need to realize that new ideas and thinking often come from people different from themselves.

9) They should be willing to have their own ideas challenged and debated.

10) They should focus on solutions, focusing on “How can we make this work?”

When a company is growing, a lot of things are added to build it up. Some of these are no longer useful and need to be dropped.

1) Determine which employees were bad hires or are no longer adding value. If you can’t rehabilitate them, encourage them to work elsewhere.

2) You should have started lots of things while the company was growing. Make sure that someone killed the things that were not great.

3) Examine product features to see if they are still desired by customers.

4) Only call a meeting if it is beneficial to all attendees. As a company grows, so do the number of useless meetings.

5) Make sure that all reports are useful, and get rid of the ones that are not. Also, automate as many as possible.

6) Examine all processes to make sure they are still efficient. New technologies may have made some archaic.

7) Prevent your company from becoming too bureaucratic. Eliminate all non-essential policies and practices.

8) Keep all software up to date, review it regularly.

If you cannot “throw them”, assign someone to the task that can.

Marketers fall into 2 categories:

They either make their customers smarter, believing that the more the people they sell to know the better that they will do, OR that they benefit the most when they work to make their customers dumber. In this case, the less their customers know about options, the easier they are to manipulate and the more helpless they are.

If just one supplier enters the field and works to make people smarter, the competition has a hard time responding with a dumbness offensive. They can attempt to confuse the customer, but sooner or later the inevitability of information spreading works in favour of those that bet on it.

The moral of the story, making your customers smarter is always the best strategy in the long run.

This plunger tip was developed a number of years ago by Allper of Switzerland.  It has evolved over time in response to changing market demands, without compromising its original mandate of performing its function most effectively at the least cost to the die caster.

The body of the plunger tip is of beryllium copper for its high coefficient of thermal expansion.  A conventional plunger tip screws directly onto the hollow plunger rod.  With the ARP, a stainless steel tip holder is screwed onto the shot rod, and the copper tip is securely fastened to it with a quick release bayonet type connector.  The front of the steel holder lies in full contact with the inside face of the plunger tip, and absorbs the total pressure of the shot.   The face can then be very thin, for better heat exchange.

The water flow is from the center of the shot rod, through the stainless holder, and directly to the inside face of the plunger tip where a turbulent flow is generated to maximize the heat transfer.  It then goes through four channels to the circular external coolant return passage.

Beryllium copper is an ideal medium to dissipate heat from the plunger to the cooling water.  It is, of course, not nearly as wear-resistant as the steel of the shot sleeve. Since the tip was then dimensionally stable, and the gap controllable, this problem was resolved with the development of a steel-wear ring.  This tempered steel ring rests freely in a groove machined near the front of the plunger tip..  It is split, and expands against the inside wall of the shot sleeve. Only the ring wears, not the copper body.  The wear ring is easily removed or installed with a special hand tool in about 5 minutes.

The die end of the shot sleeve is chamfered to compress the ring and guide it back into the sleeve.  Because the ring is flexible, it makes continuous contact with the inside of the shot sleeve.  Flash, which is a major cause of wear, is essentially eliminated.  Shot speeds are consistent.   Since the expanding wear ring ensures a secure seal between the plunger and the shot sleeve, a better vacuum can be drawn.

As only the long-lasting steel wear ring is replaced instead of an entire copper body, the cost of consumables is considerably reduced.

With a conventional tip, failure of the body is from wear.  Failure of the ARP body is only from thermal and pressure fatigue.  Operating life is therefore many times longer.

An additional advantage is that the face of the ARP is considerably cooler than that of other plunger tips.  This cools the biscuit much faster, and reduces the cycle time significantly.

This does not compromise compression, because since the wear ring remains relatively hot, while the face of the tip is much cooler, the outside of the biscuit tends to remain liquid slightly longer, allowing better than usual compression.

It is not uncommon for die casters to attempt to reduce cycle time by cooling the die end of the shot sleeve.  This unfortunately tends to shrink the sleeve at the point  where the plunger tip is hottest, and is likely at its greatest diameter.

The telephone does not provide any information about status, so we are constantly interrupting one another when calling.

The alternate tools that we have at our disposal are more polite. Instant messaging lets us detect whether our friends are busy without our bugging them. Texting lets us ping one another asynchronously. They also offer more time to think about what we want to say.

Here’s my challenge, “If I suddenly decide I want to call you, I have no way of knowing whether you are busy, and you have no idea why I am calling. Then once I have you on the phone, we have to start by having a conversation to figure out whether it is OK to have a conversation! “ Voice calls are also very emotionally laden, which is why it is so exhausting to be interrupted by one. Voice mail is even more excruciating. Studies have shown that more than 20% of all voice messages are never listened to.

Are we becoming an “always on society”? We are actually moving away from the demand that everyone be available immediately. Many people prefer to coordinate important calls in advance using email or text messaging.

According to Nielsen, the average number of mobile phone calls we make each year has been dropping since 2007. And they are getting shorter.

Is this the death of the telephone, as we know it? I expect that the telephone will survive, but the number of calls we make will continue to decrease, but their length will increase. Voice calls will be reserved for the sort of deep discussion that they do best.