When your associate drops in for a chat, you need to drop more than hints if you want to cut the chat and chatter. It sounds like you have been letting him talk himself out, and by doing so, you are enabling the very behavior you would like to curtail.
You can start with body language. When he walks in, you should look up quickly, nod, give a friendly wave that indicates you are deep at work, and then get back to whatever you were doing. When he sees you are concentrating on your work and not on him, he may pick up the cue and start to leave. As he is doing so, you can say, “Sorry…let’s talk tomorrow.”
Another body language strategy is to stand up when he enters. People are not likely to sit down and start talking when the person they are visiting stands up.
If your body language does not speak loudly to him, you should use spoken language. When he enters, politely tell him that you are busy and cannot talk, especially since you are leaving at 6:00. Then suggest that you meet at lunch or during a break tomorrow.
Regardless of your approach, when the conversations stop, he will too.
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