Can you use a material resource to drive a task duration?

[chris]

I am trying to use a custom number or the units assigned to a task to drive
the duration of the task based on how long it takes to process each unit of a
material resource. The units will be imported from an excel spreadsheet for
several hundred tasks on a weekly basis.

 

[Steve House [MVP]]

Material resources do not have working time associated with them, thus no
calendar, thus don't drive durations. You can go the other way, with the
duration driving the number of units of a resource that will be consumed by
entering the resource assignment as "units/time." For example. if task
Fidget lasting 5 hours used Widgets you could enter "5/hr" in the resource
assignment box and Project would calculate that this task would consume 25
Widgets. If the duration changed to 10 hours, the Widget consumption would
change to 50 Widgets.

You mentioned using Excel to compute the number of units processed - you
could go one step father and calculate the required duration to process X
widgets in your worksheet instead of trying to do it in Project and then use
OLE linking (In Excel, Copy - In Project, Paste Special, Paste Link, Text
Data) to copy the result of the calculation into the duration column of your
project file for the task in question. A conceptual caution - material
resources are used up, *consumed* by tasks, not *produced* by tasks.

 

[Glenn]

Chris,

I'm still trying to understand Project's Material resource concept but thought
I'd share how I approach materials in a job.

With a given resource (or a crew with multiple resources) you can determine
the "daily output" of the crew or resource for installing an item. For
example,
if you have concrete block that can be installed at a rate of 1000 SF/day,
then the duration to complete the task to put up 10000 SF of block would be
10 days.

Of course, you need good cost data to back up this approach but for many
industries, this info is available.

Hope this helps

 

[Steve House [MVP]]

Material resources are either materials consumed by doing the task (fuel,
electricity, etc) or materials incorporated into the task's deliverable. In
your concrete block example, if I need to build a cinder block retaining
wall that is 50 feet long and 6 feet high, it will take the same number of
blocks whether it takes us a week or a month to complete the wall. When we
estimate the duration, we look at the rate at which our crew can install the
blocks and the length of the wall to be erected. The duration is only
indirectly dependent on the number of blocks. What is going to most
directly control the duration is how many feet of wall the crew can put in
during during each hour they work, which may, in turn, be influencedby how
many men we have in the crew. Their calendars determine how much elapsed
time will be required to put in the necessary number of work hours to
complete the wall

When MS Project accounts for resources, duration and timeframe is controlled
by the amount of work to be done, the number of work resources available to
do it and their work schedules, and ignores material resources. On the
other hand, the total cost of the task is determined by the wages of the
resources times the hours of work they put in plus the cost of the materials
they use up. Of course you can use the method you mentioned to compute the
amount of work that is required but that's always a calculation you need to
do on your own and isn't built in to Project itself. You could do it with
calculated fields but you'd need to be careful in how you set it up, making
sure the compuation dropped into the work field instead of the duration
field.