Design Capacity - What does 'Design Capacity' (or 'Rated Capacity') mean?

samsung

Inactive Registered Visitor
#1
What does 'design capacity' (or 'rated capacity') mean and what factors does the manufacturer take into consideration while declaring the 'design capacity' of the equipment?

e.g. if the manufacturer has expressed the design capacity of a plant as 6000 tons per day, is it equivalent to 2.19 million tons per annum given the fact that the equipment does require scheduled maintenance and also there are unplanned downtime, delays, max. process efficiency and various other factors that could adversely affect the actual production capacity.

In short, what I'm interested to know is how to determine the annual production capacity if the designed capacity is expressed in tons per day or tons per hour.

Thanks in advance for your valuable inputs.
 

Chennaiite

Never-say-die
#2
Overall Equipment Effectiveness(OEE) which is a combination of Utilization, Efficiency and Quality will play a role in deciding actual capacity. Normally when a Manufacturer claims his Capacity, it is better to get into the details of whether OEE is taken into account or otherwise.
 

somashekar

Super Moderator
Staff member
Super Moderator
#3
What does 'design capacity' (or 'rated capacity') mean and what factors does the manufacturer take into consideration while declaring the 'design capacity' of the equipment?

e.g. if the manufacturer has expressed the design capacity of a plant as 6000 tons per day, is it equivalent to 2.19 million tons per annum given the fact that the equipment does require scheduled maintenance and also there are unplanned downtime, delays, max. process efficiency and various other factors that could adversely affect the actual production capacity.

In short, what I'm interested to know is how to determine the annual production capacity if the designed capacity is expressed in tons per day or tons per hour.

Thanks in advance for your valuable inputs.
Design capacity is the design input of safe maximum limit per unit time. This unit time may be cycle dependent of the equipment. For example a STP capacity can be in CMD (cubic meters per day), For a blower it can be in CFM (cubic foot per minute) For a EOT it can be SWL (Safe working load) for a water filter system, it can be LPM (Litre per minute)
The usage can be played around this capacity but cannot be expected to perform to extrapolated time to annual levels. This will be just one factor alongside several other to determine or plan annual capacity.
 

samsung

Inactive Registered Visitor
#4
Thanks for the responses.

I put up my question in another way -

Design capacity = 6000 tons per day

Annual capacity = 6000 x 365 or 2190000 tons

Assuming 35 days for preventive maint. and other unplanned downtime,

So the actual production would be = 6000 x 330 or 1980000 tons

Can the design capacity be calculated as = 2190000/330 or 6636 tons per day ?
 

somashekar

Super Moderator
Staff member
Super Moderator
#5
Thanks for the responses.

I put up my question in another way -

Design capacity = 6000 tons per day

Annual capacity = 6000 x 365 or 2190000 tons

Assuming 35 days for preventive maint. and other unplanned downtime,

So the actual production would be = 6000 x 330 or 1980000 tons

Can the design capacity be calculated as = 2190000/330 or 6636 tons per day ?
Design capacity is never deduced from production capacity. Rather production capacity is factored over design capacity.
 

samsung

Inactive Registered Visitor
#6
Design capacity is never deduced from production capacity. Rather production capacity is factored over design capacity.
Do you mean Capacity utilization,

Utilization = Actual output / Design capacity

In this case, it would come out to be 110.6%
 

somashekar

Super Moderator
Staff member
Super Moderator
#7
No. I used the word factored and not calculated.
Design capacity is a constant. Moreover a management decision to install a higher design capacity equipment can be taken with future in mind. This capacity cannot be governing utilization.
Utilization = Actual output / Design capacity
Denominator is a constant, so utilization is directly proportional to output. I cannot know from where you get this equation.
 

Chennaiite

Never-say-die
#8
Thanks for the responses.

I put up my question in another way -

Design capacity = 6000 tons per day

Annual capacity = 6000 x 365 or 2190000 tons

Assuming 35 days for preventive maint. and other unplanned downtime,

So the actual production would be = 6000 x 330 or 1980000 tons

Can the design capacity be calculated as = 2190000/330 or 6636 tons per day ?
Here's my understanding.
Assuming that there is only one Equipment involved, lets say the Utilization of the Equipment is 90%, Efficiency is 90% and Quality is 100%. Overall Equipment Effectiveness is 90X90X100 i.e. 81%. Now your actual capacity would be 6000X0.81 i.e. 4860 tons per day or 1773900 tons annual.

Remember, Utilization is not just about Preventive Maintenance and Unplanned downtime, it also includes Daily Meeting, 5S, Setting time, etc. Efficiency of the equipment is another important factor in Capacity calculation. The theoretical Cycle time can be 1 min/part, but after one hour of continuous operation the equipment may yield only 45 parts (with 75% efficiency). And number of bad parts produced, all these decide the actual capacity.
 

samsung

Inactive Registered Visitor
#9
Here's my understanding.
Assuming that there is only one Equipment involved, lets say the Utilization of the Equipment is 90%, Efficiency is 90% and Quality is 100%. Overall Equipment Effectiveness is 90X90X100 i.e. 81%. Now your actual capacity would be 6000X0.81 i.e. 4860 tons per day or 1773900 tons annual.

Remember, Utilization is not just about Preventive Maintenance and Unplanned downtime, it also includes Daily Meeting, 5S, Setting time, etc. Efficiency of the equipment is another important factor in Capacity calculation. The theoretical Cycle time can be 1 min/part, but after one hour of continuous operation the equipment may yield only 45 parts (with 75% efficiency). And number of bad parts produced, all these decide the actual capacity.
Thanks Chennaiite for your response. The reason behind asking this question is that I couldn't recollect myself when recently I came across a news article wherein it was claimed by one of the plant heads that the designed capacity of the plant supplied to them was 6500 tpd (standard terminology that the suppliers use to express the plant capacity) but after process optimization (???), they could actually produce 2584000 tons of product per annum or 7600 tpd (340 days or 8160 hours of operation in a year) without any engineering modifications. (I assume 98% as the highest efficiency at which they might have operated the plant.)

So, the question is rephrased as - Is it possible for an equipment to deliver higher output than its actual design/ rated capacity? If not then either the achieved output or the rated capacity in the above case is misleading.
 
#10
Thanks Chennaiite for your response. The reason behind asking this question is that I couldn't recollect myself when recently I came across a news article wherein it was claimed by one of the plant heads that the designed capacity of the plant supplied to them was 6500 tpd (standard terminology that the suppliers use to express the plant capacity) but after process optimization (???), they could actually produce 2584000 tons of product per annum or 7600 tpd (340 days or 8160 hours of operation in a year) without any engineering modifications. (I assume 98% as the highest efficiency at which they might have operated the plant.)

So, the question is rephrased as - Is it possible for an equipment to deliver higher output than its actual design/ rated capacity? If not then either the achieved output or the rated capacity in the above case is misleading.
My interpretation is this particular Manufacturer has increased his 'Design Capacity' through Process Optimization resulting in increase in actual output. Doesn't look misleading for me.
 
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