Negative Lag in Procurement activities

The design is completed and so the product can be manufactured, quality checked and ready for delivery. I don’t think the quantity can be worked out since what can be stated is the first batch of product is ready for delivery. In many situation, the manufacture rate is slow at front end and progressively increase to achieve a smooth production.

I had a similar assesment. but in effect, my question was on the validity of "logic used". was it not possible to link these activities i.e. manufacture of equipment and delivery of of first kit to site, with a SS and Lag rather than negative lags? when the above logic is progressed, the delivery dates change showing the dependence of delivery on progress made. what is the analytical approach to such situation.
hashmi,
UK

Instead of SS or FS with -ve lag, my practice is to split the front activities into 2. With first include "Design, set up production line, manufacture the first batch" and the second is "manufacture the rest". Also first activity have FS to second one and "Delivery of first batch".
Then critical is more clear, I think.

Conclusively, to avoid negative lag in procurement activties or others, always use links for activities as SS or FS in CPM.

I prefer a FS with zero lag approach rather SS with +ve lag. The output of SS have no significant difference when compare with FS with -ve lag.

It is a case of Theory versus Practice. In theory, SS with a positive lag is equal to FF with a negative lag, in an unstatused baseline schedule. In practice, as soon as you have statused the predecessor activity as starting, the two different approaches divert from each other.

Once you begin your predecessor activity, the SS with positive lag will schedule the successor activity to begin the set number of days in the future regardless of what happens after that. On the other hand, the FF negative lag will still schedule the successor activity to begin based upon the status and progress of the predecessor activity.

Once started, a delay in the predecessor activity will have no effect on the successor nor even on project completion when you use a SS with a positive lag. In most cases, a delay to that same predecessor activity will delay the start of the successor when you use a FF with negative lag. There is a difference.

exactly roland! now that is the question that requires a little exlaboration. in each of the successive progress reports submitted by the subcontractor, there is a difference of delivery date..i just wonder, from claim’s point of view, that is there a point that can be made against the use of this ligic by the subcontractor or is it just normal practice.
Regards
Hashmi