357 Process analysis homework answer

[Ted_Li]

Hi All,

Please see my answer for the process hw and comment.

Thanks!
Ted
==================================
357 Process analysis homework

a. What is the bottleneck now?
With 3 parallel conveyers that each produced a patty every 6
seconds, Brand Y burger could produce 1 patty every 2 seconds (6/3=2).
Now u=3600/2=1800 (/hour). Clearly Veggie Prep with u=1400/hour
becomes bottleneck now.

b. What is the cycle time for the process?

3600/1400 = 2.57 seconds

c. What is the throughput time?

The same as before, since 2 min cooking is required.
2 min cooking + 2.5 sec assy + 12 sec microwave = 2 min 14.5
seconds + queues

d. If they continue to sell 162,400 burgers per month, what is their
capacity utilization?

Capacity of System: 1 every 2.57 seconds = 23.33/min, 1400/hr, or
33600/day {24 hours}.
If they continue to sell 162,400 burgers per month = 5413/day, the
capacity utilization is 5413/33600 = 16.1%

e. At what stages in the process would you expect work in progress to
pile up?

Between broiler and assembly there will be a queue due to slow
handling of Veggie Prep.

[Nicholas Woo]

Ted,

Wouldn't the revised throughput time be based on the Veggie Prep cycle time and not the cook time since Veggie Prep is the "new" bottleneck, and they're parallel processes?

[Xiuya Li]

I did this because you need 2 mins to cook anyhow, you can not use 2.57seconds to replace this 2 mins since you won't get enough time to cook therefore the food is not saleble.

 

In the original slides, you can see 2 mins is used, not 1 min even though there are 2 paralle broilers.

 

Thanks!
Ted

 

(This is my opinion, not confirmed with professor)

[Nicholas Woo]

I agree that 2 minutes should still be used regardless of how many broilers there are, but only if the broiler is still the bottleneck process; which it isn't if a 3rd broiler is added, since the process time increases from 1200/hr to 1800/hr. If it takes 2.57 minutes to do the Veggie Prep, and it takes 2.00 minutes to prepare 20 patties, then the throughput time should be measured based on the Veggie Prep (the new bottleneck) since at a minimum, it will take a minimum of 2.57 minutes before assembly can take place.

Nick

[Nicholas Woo]

Sorry, let me retract my last statement. You were correct, Veggie Prep is 2.57 seconds and not 2.57 minutes. I suppose this is saying "one" veggie can be prepared every 2.57 seconds? But how many veggies are required to assemble a single hamburger? I'm still a little confused because it seems like we're not comparing equal quantities here. The meat is being measured in quantities of 20, yet it's unclear what quantities of veggies are required per patty.

[Ashish Swaroop]

Ted,

The queue between Broiler and Assembly will be because Broiler can give 1800/hr now and Assembly can handle 1440/hr, not because veggie prep because it is anyway bottleneck.

Is that correct reasoning?

regds

Ashish

On Fri, Apr 15, 2011 at 11:42 AM, Ted_Li <xiu...@gmail.com> wrote:

[Nicholas Woo]

Ted,

If the cycle time for cooking the meat is still 2 minutes irrespective of how many broilers we add, then why does veggie prep become the bottleneck? I realize that this answer can be concluded by evaluating bottlenecks based on the process times alone, but if we consider cycle times only, it will take a minimum of 2 minutes to produce even 1 patty since that's the minimum amount of time a patty needs to be cooked before being edible (in other words, the 1 patty every 2 seconds cycle time is merely an average, and should be trumped by the 2 minute cooking time required).

So - unless any of the other processes have a longer cycle time than 2 minutes, I believe the bottleneck should still remain at the Broilers despite the addition of one. Does anyone disagree with this?

--Nick 

On Fri, Apr 15, 2011 at 12:05 PM, Xiuya Li <xiu...@gmail.com> wrote:

[Xiuya Li]

Sorry for my delayed response, worked till now :-)

 

Ashish: I just did 2 comparison, a) 1800>1440 (piled up here)

                                               b) 1400<1440 (no queue in average)

 

Nick: you said "unless any of the other processes have a longer cycle time than 2 minutes, I believe the bottleneck should still remain at the Broilers despite the addition of one. Does anyone disagree with this?" No, I don't agree. no process has cycle time of 2 minutes here. 2 minutes is part of throughput time, the cycle time for cooking is now 2 second, the throughput "contribution" is 2 minutes from this process. For Veggie Prep, we can assume there is no time period requirement, aka, you can go as fast as you could.

 

Thanks!

Ted (not confirmed with professor)

[Savitha]

I agree with Ted. Additional broiler will only contribute to overall
availability of the patties and this has gone up to 1800/hr.
This did not reduce the the requirement (health requirement) that each
patty has to be cooked for 2 minutes.
Each conveyor will still process 20 patties each. The number of
patties process per hour per conveyor is still the same - 600/hr and
this ensures the required cook time. It has just changed the cycle
time as we can process more patties.
3600/1800 = 2 sec.
I am getting the same answers as Ted.

thanks,
Savitha

On Apr 15, 6:26 pm, Xiuya Li <xiuy...@gmail.com> wrote:
> Sorry for my delayed response, worked till now :-)
>
> Ashish: I just did 2 comparison, a) 1800>1440 (piled up here)
>                                                b) 1400<1440 (no queue in
> average)
>
> Nick: you said "unless any of the other processes have a longer cycle time
> than 2 minutes, I believe the bottleneck should still remain at the Broilers
> despite the addition of one. Does anyone disagree with this?" No, I don't
> agree. no process has cycle time of 2 minutes here. 2 minutes is part of
> throughput time, the cycle time for cooking is now 2 second, the throughput
> "contribution" is 2 minutes from this process. For Veggie Prep, we can
> assume there is no time period requirement, aka, you can go as fast as you
> could.
>
> Thanks!
> Ted (not confirmed with professor)
>

> On Fri, Apr 15, 2011 at 5:22 PM, Nicholas Woo <nicholasj...@gmail.com>wrote:
>
> > Ted,
>
> > If the cycle time for cooking the meat is still 2 minutes irrespective of
> > how many broilers we add, then why does veggie prep become the bottleneck? I
> > realize that this answer can be concluded by evaluating bottlenecks based on
> > the process times alone, but if we consider cycle times only, it will take a
> > minimum of 2 minutes to produce even 1 patty since that's the minimum amount
> > of time a patty needs to be cooked before being edible (in other words, the
> > 1 patty every 2 seconds cycle time is merely an average, and should be
> > trumped by the 2 minute cooking time required).
>
> > So - unless any of the other processes have a longer cycle time than 2
> > minutes, I believe the bottleneck should still remain at the Broilers
> > despite the addition of one. Does anyone disagree with this?
>
> > --Nick
>

> > On Fri, Apr 15, 2011 at 12:05 PM, Xiuya Li <xiuy...@gmail.com> wrote:
>
> >> I did this because you need 2 mins to cook anyhow, you can not use
> >> 2.57seconds to replace this 2 mins since you won't get enough time to cook
> >> therefore the food is not saleble.
>
> >> In the original slides, you can see 2 mins is used, not 1 min even though
> >> there are 2 paralle broilers.
>
> >> Thanks!
> >> Ted
>
> >> (This is my opinion, not confirmed with professor)
>

> >> On Fri, Apr 15, 2011 at 11:51 AM, Nicholas Woo <nicholasj...@gmail.com>wrote:
>
> >>> Ted,
>
> >>> Wouldn't the revised throughput time be based on the Veggie Prep cycle
> >>> time and not the cook time since Veggie Prep is the "new" bottleneck, and
> >>> they're parallel processes?
>

[alex smirnov]

Hi everyone,

My answers agree with Ted 100%.  The only thing I would add, is that there's probably work piling up between Toasting and Assembly in addition to broiler =>assembly because toasting happens at 1600/hr while assembly is at a slower pace of 1440/hour

As far as the throughput vs bottleneck discussion.  It is a bit confusing, but bottleneck has to do with how quickly the process can make a finished product while it is running at capacity, while throughput is simply how long it takes a particular item to go through the entire process

for example, if there are 5 trucks going from SF to LA every hour, and it takes each truck 5 hours, the cycle time is 1 hour (one truck per hour will arrive in LA), while the throughput is still 5 hours

Hope that helps

Alex

[Girish Kumar]

Thanks Alex. I was confused about bottleneck versus throughput calculations. Your explanation helps my understanding.

 

Regards,

Girish